Information processing apparatus, power saving transition program, and power saving transition method

An information processing apparatus comprising a plurality of computation nodes each having a CPU, a cooler that cools a refrigerant in a conduit in which the refrigerant that cools the CPU of each of the plurality of computation nodes circulates, and a control node, wherein the control node decreases a cooling power of the cooler after execution of a job by the plurality of computation nodes is ended, and causes the CPU in which the execution of the job is ended to transition from a non-power saving mode to a power saving mode at a predetermined time interval a predetermined number of the CPUs at a time when a temperature of the refrigerant is equal to or more than a threshold value, and stops a process of causing the CPU to transition to the power saving mode when the temperature of the refrigerant is less than the threshold value.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-234067, filed on Dec. 6, 2017, the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to an information processing apparatus, a power saving transition program, and a power saving transition method.

BACKGROUND

In a conventional information processing apparatus having a plurality of computation nodes that generate heat as a result of execution of processes, a liquid-cooling cooler for cooling the CPU of each of the plurality of computation nodes is used to prevent the failure of the CPU caused by the heat generation.

In such an information processing apparatus having the plurality of computation nodes and the liquid-cooling cooler, from the viewpoint of power savings, it is desirable to cause a plurality of the computation nodes (CPUs) that are not executing the processes to transition from a non-power saving mode to a power saving mode having lower power consumption (amount of heat generation) to bring the computation nodes into a power saving state.

Japanese Laid-open Patent Publication No. 2015-230658 and International Publication Pamphlet No. WO2014/147691 relate to cooling of the CPU.

SUMMARY

However, the time constant of the computation node (CPU) is relatively short and a decrease in the amount of heat generation of the computation node (CPU) progresses rapidly, while the time constant of the liquid-cooling cooler is relatively long and a decrease in the cooling power of the cooler progresses gradually.

Accordingly, for example, when cooling power decrease control of the cooler is executed at the timing when execution of an assigned job is ended, and a plurality of the computation nodes (CPUs) in which the execution of the assigned job is ended are caused to transition from the non-power saving mode to the power saving mode simultaneously, the amount of heat generation of the computation nodes (CPUs) falls below the cooling power of the cooler until the decrease in cooling power catches up with the sharp decrease in the amount of heat generation. That is, the cooling power of the cooler becomes excessive and redundant.

As a result, a refrigerant (e.g., cooling water) circulating in a conduit constituting the cooler is excessively cooled by the redundant cooling power, and the temperature of the refrigerant decreases rapidly. This presents a problem where the refrigerant may be frozen and expanded, the conduit may be damaged, the refrigerant may leak from the damaged part, and peripheral electronic equipment may fail.

According to an aspect of the embodiments, an information processing apparatus comprising:

a plurality of computation nodes each having a CPU that executes an assigned job;

a cooler that cools a refrigerant in a conduit in which the refrigerant that cools the CPU of each of the plurality of computation nodes circulates; and

a control node to which the plurality of computation nodes and the cooler are connected, wherein the control node:

assigns a job to the plurality of computation nodes;

decreases a cooling power of the cooler by a predetermined extent after execution of the job by the plurality of computation nodes to which the job is assigned is ended; and

causes the CPU of each of the plurality of computation nodes in which the execution of the job is ended to transition from a non-power saving mode to a power saving mode at a predetermined time interval a predetermined number of the CPUs at a time when a temperature of the refrigerant is equal to or more than a threshold value, and stops a process of causing the CPU to transition to the power saving mode when the temperature of the refrigerant is less than the threshold value.

According to the present embodiment, it is possible to cause each of the plurality of computation nodes (CPUs) to transition from the non-power saving mode to the power saving mode while preventing the refrigerant circulating in the conduit constituting the liquid-cooling cooler from being excessively cooled.

DESCRIPTION OF EMBODIMENTS

Summary of First Embodiment

FIG. 1is a view illustrating the schematic configuration of an information processing apparatus10to which an information processing apparatus, a power saving transition program, and a power saving transition method of a first embodiment are applied. As illustrated inFIG. 1, the information processing apparatus10includes a plurality of computation nodes102to110each having a CPU1(hereinafter also referred to as a processor1or a processor chip1) that executes an assigned job, a liquid-cooling cooler127that cools a conduit121in which a refrigerant that cools the processor1of each of the plurality of computation nodes102to110circulates and the refrigerant in the conduit121, a control node101to which the plurality of computation nodes102to110and the cooler127are connected, and a temperature sensor122that detects the temperature of the refrigerant (e.g., cooling water) circulating in the conduit121.

The computation nodes102to110, the cooler127, and the temperature sensor122are connected to the control node101via a network NW.

Each of the computation nodes102to110is a computer that includes the processor1and a main memory2. The processor1of each of the computation nodes102to110executes a job execution program6loaded into the main memory2to execute a job assigned by the control node101in a non-power saving mode.

The control node101is a computer that includes a CPU101a(hereinafter also referred to as a processor101a) and a main memory101b. The control node101may also be any of the computation nodes102to110.

The processor101aexecutes a control program101d2loaded into the main memory101bto assign the job to the computation nodes102to110. In addition, the processor101aexecutes the control program101d2to cause the processor1of each of the computation nodes102to110in which execution of the job is ended and to which the job is not assigned to transition (change) from the non-power saving mode (job non-execution) to a power saving mode (job non-execution). Further, the processor101aexecutes the control program101d2to control the cooling power of the cooler127. The cooling power of the cooler127is also referred to as cooling capability, and represents an amount of heat that can be removed per unit time (the unit is a watt (W)).

The control program101d2is an example of the power saving transition program. The power saving transition program includes job assignment control for assigning the job to the computation nodes102to110, control for causing the processor1of each of the computation nodes102to110in which the execution of the job is ended and to which the job is not assigned to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution), and cooling power control for controlling the cooling power of the cooler127.

Job Assignment Control

FIG. 2is a flowchart for illustrating the job assignment control of the control program101d2.

The processor101aof the control node101executes the control program101d2to perform the following process.

The processor101aof the control node101determines whether or not a job to be assigned is present in a job queue (S10). Although not illustrated, the job queue is stored in, e.g., the main memory101bof the control node101. The job to be assigned is a job that is scheduled to be assigned to the computation node.

As the result of the determination in S10, in the case where it is determined that the job to be assigned is not present in the job queue (S10: NO), the processor101aof the control node101waits until the job to be assigned is stored in the job queue and it is determined that the job to be assigned is present in the job queue.

On the other hand, as the result of the determination in S10, in the case where it is determined that the job to be assigned is present in the job queue (S10: YES), the processor101aof the control node101determines whether or not an available node is present (S11). The available node is a computation node that is not executing the job.

As the result of the determination in S11, in the case where it is determined that the available node is not present (S11: NO), the processor101aof the control node101waits until the execution of the job is ended and it is determined that the available node is present.

On the other hand, as the result of the determination in S11, in the case where it is determined that the available node is present (S11: YES), the processor101aof the control node101assigns the job to be assigned to the available node (S12).

Cooling Power Control

FIG. 3is a flowchart for illustrating the summary of the cooling power control of the control program101d2.

The processor101aof the control node101executes the control program101d2to perform the following process.

In the case where the computation node to which the job is assigned in S12(hereinafter also referred to a job-assigned node) starts the execution of the job (S19: YES), the processor101aof the control node101performs transition control in which the job-assigned node is caused to transition from the power saving mode to the non-power saving mode (S24). Concurrently with S24, the processor101aof the control node101executes cooling power increase control of the cooler127(S25). Specifically, the processor101aof the control node101controls the cooling power of the cooler127such that the cooling power increases by a predetermined extent.

On the other hand, in the case where the computation node ends the execution of the job (S19: NO, S20: YES), the processor101aof the control node101performs the transition control in which the processor1of a job-end node is caused to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) (S21). The job-end node is the computation node to which the job is assigned in S12and in which the execution of the assigned job is ended.

Concurrently with S12, the processor101aof the control node101executes cooling power decrease control of the cooler127(S22). Specifically, the processor101aof the control node101controls the cooling power of the cooler127such that the cooling power decreases by a predetermined extent.

Thereafter, the processor101aof the control node101repeatedly executes S19to S25. The present embodiment relates to an improvement in the control in each of S21and S22.

FIGS. 4A to 4Care views for illustrating the cooling power control of the control program101d2in detail.

FIG. 4Aillustrates an example of the change of the state of each of the computation nodes102to110(processors1) correspondingly to the time axis. As illustrated inFIG. 9, the state of each of the computation nodes102to110(processors1) includes the non-power saving mode (job execution), the non-power saving mode (job non-execution), and the power saving mode (job non-execution). Power consumption (amount of heat generation) decreases in this order.

An area A1hatched by a first hatch H1inFIG. 4Adenotes that the state of the corresponding computation node (processor1) is the non-power saving mode (job execution).

In addition, an area A2(a plurality of squares) hatched by a second hatch H2inFIG. 4Adenotes that the state of the corresponding computation node (processor1) is the non-power saving mode (job non-execution). Further, an area A3hatched by a third hatch H3inFIG. 4Adenotes that the state of the corresponding computation node (processor1) is the power saving mode (job non-execution).

InFIG. 4B, an example of the change of the total amount of heat generation of the processors1of the respective computation nodes102to110(corresponding toFIG. 4A) is indicated by a dotted line G1, and an example of the change of the cooling power of the cooler127is indicted by a solid line G2. InFIG. 4C, an example of the change of the temperature of the refrigerant circulating in the conduit121that corresponds toFIG. 4Ais indicated by a solid line G3.

Before Time T1

As illustrated inFIG. 4A, before time T1, the job is not assigned to the processor1of each of the computation nodes102to110, and the processor1of each of the computation nodes102to110operates in the power saving mode (job non-execution) (S10).

As indicated by the dotted line G1inFIG. 4B, before time T1, the total amount of heat generation of the processors1of the respective computation nodes102to110is P1 watts (W).

As indicated by the solid line G2inFIG. 4B, before time T1, the cooling power of the cooler127is the cooling power that substantially matches the total amount of heat generation of the processors1in order to reduce an increase in temperature resulting from the total amount of heat generation of the processors1of the respective computation nodes102to110.

Thus, before time T1, the total amount of heat generation of the processors1of the respective computation nodes102to110and the cooling power of the cooler127counterbalance each other at P1 watts.

Consequently, as indicated by the solid line G3inFIG. 4C, before time T1, the temperature of the refrigerant circulating in the conduit121is controlled to a temperature Temp1that allows the processors1to operate properly and prevents the refrigerant from being frozen.

Time T1

Next, the processor101aof the control node101executes the job assignment control illustrated inFIG. 2and, as illustrated inFIG. 4A, assigns the job to the computation nodes102to110at time T1(S11). Subsequently, the processor101aof the control node101instructs the computation nodes102to110to execute the assigned job via the network NW.

As illustrated inFIG. 4A, at time T1, the processor1of each of the computation nodes102to110transitions from the power saving mode (job non-execution) to the non-power saving mode, and executes the job assigned (submitted) by the control node101in the non-power saving mode (S12).

When the processor1of each of the computation nodes102to110executes the assigned (submitted) job in the non-power saving mode, the non-power saving mode (job execution) is higher in power consumption (amount of heat generation) than the power saving mode (job non-execution), and hence, as indicated by the dotted line G1inFIG. 4B, the total amount of heat generation of the processors1of the respective computation nodes102to110increases to P2 watts.

The processor101aof the control node101executes the cooling power increase control of the cooler127to increase the cooling power of the cooler127in order to reduce the increase in temperature resulting from the total amount of heat generation of the processors1of the respective computation nodes102to110in the non-power saving mode (job execution) (S13). Specifically, the control node101performs the control such that the cooling power of the cooler127is increased so as to counterbalance the total amount of heat generation of the processors1of the respective computation nodes102to110in the non-power saving mode (job execution).

Note that the time constant of each of the computation nodes102to110(processors1) is relatively short (e.g., about several seconds to several tens of seconds), and hence the total amount of heat generation of the processors1of the respective computation nodes102to110increases rapidly due to the transition to the non-power saving mode (job execution). In contrast to this, the time constant of the cooler127is relatively long (e.g., about several tens of minutes), and hence the cooling power of the cooler127does not increase rapidly even when the cooling power increase control of the cooler127is performed, the cooling power thereof increases gradually from time T1and, after a lapse of a predetermined time period, the total amount of heat generation of the computation nodes102to110in the non-power saving mode (job execution) and the cooling power of the cooler127counterbalance each other at P2 watts finally. Consequently, as indicated by the solid line G3inFIG. 4C, the temperature of the refrigerant circulating in the conduit121increases gradually, and the increase stops at a temperature Temp2.

Time T2

Next, as illustrated inFIG. 4A, the processor1of each of the computation nodes102to110ends the execution of the assigned job at time T2, and transitions from the non-power saving mode (job execution) to the non-power saving mode (job non-execution) (S14).

In the case where the execution of the assigned jobs is ended in this manner, from the viewpoint of power savings, it is desirable to cause the processor1of each of the computation nodes102to110in which the execution of the assigned job is ended to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) simultaneously to bring the processors1into a power saving state, and execute the cooling power decrease control of the cooler127in order to prevent the refrigerant of the cooler127from being excessively cooled (frozen) (S21, S22inFIG. 3).

However, as described above, the time constant of the change of the cooling power of the refrigerant after control for switching the cooling power of the cooler127is relatively long (e.g., about several tens of minutes), and hence a decrease in cooling power after the cooling power decrease control of the cooler127progresses gradually. In contrast to this, the time constant of the change of the amount of heat generation of the computation nodes102to110(processors1) is relatively short (e.g., about several seconds to several tens of seconds), and hence a decrease in the total amount of heat generation after control for decreasing the amount of heat generation of the computation nodes102to110(processors1) progresses rapidly.

Consequently, for example, when the cooling power decrease control of the cooler127is executed at the timing when the execution of the assigned job is ended, and the processor1of each of the computation nodes102to110in which the execution of the assigned job is ended is caused to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) simultaneously, the total amount of heat generation of the processors1of the respective computation nodes102to110falls below the cooling power of the cooler127until the decrease in cooling power catches up with the sharp decrease in the amount of heat generation. That is, the cooling power of the cooler127becomes excessive and redundant.

As a result, the refrigerant circulating in the conduit121is excessively cooled by the redundant cooling power, and the temperature of the refrigerant decreases rapidly. Consequently, the refrigerant may be frozen and expanded, the conduit121may be damaged, the refrigerant may leak from the damaged part, and peripheral electronic equipment may fail.

To cope with this, in the first embodiment, the processor1of each of a plurality of the computation nodes in which the execution of the job is ended is caused to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) one by one slowly and gradually (at predetermined time intervals) while the temperature of the refrigerant circulating in the conduit121is monitored such that the cooling power of the cooler127does not become excessive. Specifically, the cooling power control (S21, S22) illustrated inFIG. 3is executed.

This enables the change of the decrease in the total amount of heat generation of the computation nodes to follow the change of the gradual decrease in the cooling power of the cooler127.

As a result, it is possible to cause the processor1of each of the computation nodes102to110to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) while preventing the refrigerant circulating in the conduit121from being excessively cooled.

Cooling Power Control (S21, S22)

FIG. 5is a flowchart for illustrating the cooling power control (S21, S22) illustrated inFIG. 3.

In the case where the execution of the job by the computation nodes102to110to which the job is assigned is ended (S30), the processor101aof the control node101determines whether or not a temperature T of the refrigerant circulating in the conduit121that is detected by the temperature sensor122is equal to or more than a threshold value Th (S31).

As a result, in the case where the temperature T of the refrigerant is less than the threshold value Th (S31: NO), the processor101aof the control node101executes the cooling power decrease control of the cooler127(S32) to decrease the cooling power of the cooler127by a predetermined extent.

On the other hand, as the result of the determination in S31, in the case where the temperature T of the refrigerant is equal to or more than the threshold value Th (S31: YES), the processor101aof the control node101causes the processor1of each of a plurality of the computation nodes in which the execution of the job is ended in S30to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) one by one at predetermined time intervals (S33).

Subsequently, the processor101aof the control node101waits a predetermined time period (S34), and then repeatedly executes S31to S34.

According to the control inFIG. 5, when the processor101aof the control node101executes the control program101d2to end the job (S30), the processor101aof the control node101performs the cooling power decrease control of the cooler127(S32) when the temperature T of the refrigerant<the threshold value Th is satisfied (S31: NO). This allows the cooling power of the cooler127to decrease gradually, and allows the temperature of the refrigerant to increase gradually. Subsequently, when the temperature T of the refrigerant>the threshold value Th is satisfied (S31: YES), the processor101aof the control node101repeats the transition control in which the processor1of each of the computation nodes in which the job is ended is caused to transition to the power saving mode (job non-execution) one by one or a predetermined number of the processors1at a time at predetermined time intervals (S34). This enables the total amount of heat generation of the processors1of the respective computation nodes102to110to decrease gradually so as to follow the gradual decrease in the cooling power of the cooler127.

After a while, when the temperature T of the refrigerant<the threshold value Th is satisfied, the processor101aof the control node101executes the cooling power decrease control of the cooler127(S32) again, and stops the control in which the processor1of each of the job-end nodes is caused to transition to the power saving mode (job non-execution) one by one at predetermined time intervals (S33, S34).

Next, with reference toFIGS. 4A to 4C, the cooling power control (S21, S22) illustrated inFIG. 3will be described in detail.

After the job is ended, the processor101aof the control node101determines whether or not the temperature T of the refrigerant circulating in the conduit121that is detected by the temperature sensor122is equal to or more than the threshold value Th at predetermined timings between T2and T12.

Subsequently, in the case where the temperature T of the refrigerant detected by the temperature sensor122is equal to or more than the threshold value Th, the processor101aof the control node101causes the processor1of each of a plurality of the computation nodes102to110in which the execution of the jobs is ended to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) one by one slowly and gradually (at predetermined time intervals).

For example, as indicated by the solid line G3inFIG. 4C, the temperature T of the refrigerant detected by the temperature sensor122is equal to or more than the threshold value Th at time T2immediately after the job is ended (S15), and hence the processor101aof the control node101changes the mode of the processor1of the computation node102from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) (S16).

In addition, the temperature T of the refrigerant detected by the temperature sensor122is equal to or more than the threshold value Th between time T4and time T6, and hence the processor101aof the control node101causes the processor1of each of the computation nodes103to105to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) one by one at their respective timings between time T4and time T6(S21).

Further, the temperature T of the refrigerant detected by the temperature sensor122is equal to or more than the threshold value Th also between time T8and time T12, and hence the processor101aof the control node101causes the processor1of each of the computation nodes106to110to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) one by one at their respective timings between time T8and time T12(S26).

On the other hand, when the mode of the processor1of each of the computation nodes102to110is changed from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) (S16, S21, S26), there are cases where the total amount of heat generation of the processors1of the respective computation nodes102to110falls below the cooling power of the cooler127. That is, there are cases where the cooling power of the cooler127becomes excessive and redundant. The same applies to the case where the processor1of each of the computation nodes102to110is caused to transition from the non-power saving mode (job execution) to the non-power saving mode (job non-execution) having lower power consumption (amount of heat generation) (S14).

For example, at time T2, the processor1of each of the computation nodes102to110ends the assigned job, and transitions from the non-power saving mode (job execution) to the non-power saving mode (job non-execution) having a smaller amount of heat generation (S14). In addition, at time T2, the mode of the processor1of the computation node102is changed from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) having a smaller amount of heat generation (S16).

With this, the amount of heat generation G1of the processor1having the relatively short time constant decreases rapidly and, as indicated by the dotted line G1and the solid line G2between time T2and time T3inFIG. 4B, there are cases where the total amount of heat generation of the processors1of the respective computation nodes102to110falls below the cooling power of the cooler127. That is, there are cases where the cooling power of the cooler127becomes excessive and redundant.

As a result, the refrigerant circulating in the conduit121is excessively cooled by the redundant cooling power and, as indicated by the solid line G3between time T2and time T3inFIG. 4C, the temperature of the refrigerant decreases rapidly. Consequently, the refrigerant may be frozen and expanded, the conduit121may be damaged, the refrigerant may leak from the damaged part, and peripheral electronic equipment may fail.

To cope with this, in the case where the temperature T of the refrigerant detected by the temperature sensor122is less than the threshold value Th, the processor101aof the control node101stops the change of the mode of the computation node to the power saving mode, and executes the cooling power decrease control of the cooling power of the cooler127to decrease the cooling power of the cooler127. That is, the cooling power of the cooler127is decreased while the total amount of heat generation of the processors1of the respective computation nodes102to110is maintained. Specifically, the control node101controls the cooling power of the cooler127such that the cooling power decreases by a predetermined extent. This allows the cooling power of the cooler127to decrease gradually due to its relatively long time constant.

For example, at time T3, the temperature T of the refrigerant detected by the temperature sensor122is less than the threshold value Th (S17), and hence the processor101aof the control node101stops the change of the mode of the processor1of the computation node103to the power saving mode (S18), and executes the cooling power decrease control of the cooling power of the cooler127to decrease the cooling power of the cooler127by a predetermined extent (S19).

As indicated by the dotted line G1and the solid line G2between time T3and time T4inFIG. 4B, this enables the total amount of heat generation of the processors1of the respective computation nodes102to110to exceed the cooling power of the cooler127. That is, the total amount of heat generation of the processors1of the respective computation nodes102to110becomes excessive.

As a result, as indicated by the solid line G3between time T3and time T4inFIG. 4C, the temperature of the refrigerant circulating in the conduit121starts to increase. This prevents the refrigerant circulating in the conduit121from being excessively cooled.

Note that, since the time constant of the cooler127is relatively long, even when the cooling power decrease control of the cooler127is executed, the cooling power of the cooler127does not decreases rapidly but decreases gradually, as indicated by the solid line G2between time T3and time T4inFIG. 4B.

When the temperature of the refrigerant circulating in the conduit121starts to increase, and the temperature of the refrigerant detected by the temperature sensor122becomes equal to or more than the threshold value Th (see, e.g., time T4to time T6inFIG. 4C), the processor101aof the control node101resumes the process of causing the processor1of each of the computation nodes103to105to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) one by one at their respective timings between time T4and time T6(S21).

Thus, when the processor1of each of the computation nodes103to105is caused to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) one by one, there are cases where the total amount of heat generation of the processors1of the respective computation nodes102to110falls below the cooling power of the cooler127at time T6. That is, there are cases where the cooling power of the cooler127becomes excessive and redundant.

As a result, the refrigerant circulating in the conduit121is excessively cooled by the redundant cooling power and, as indicated by the solid line G3between time T6and time T7inFIG. 4C, the temperature of the refrigerant decreases rapidly. Thus, the risk of freezing the refrigerant is increased again.

To cope with this, in the case where the temperature T of the refrigerant detected by the temperature sensor122is less than the threshold value Th, the control node101stops the change of the mode of the computation node to the power saving mode, and executes the cooling power decrease control of the cooling power of the cooler127to decrease the cooling power of the cooler127. That is, the cooling power of the cooler127is decreased while the total amount of heat generation of the processors1of the respective computation nodes102to110is maintained.

For example, the temperature T of the refrigerant detected by the temperature sensor122is less than the threshold value Th at time T7(S22), and hence the processor101aof the control node101stops the change of the mode of the processor1of the computation node103to the power saving mode (S23), and executes the cooling power decrease control of the cooling power of the cooler127to decrease the cooling power of the cooler127by a predetermined extent (S24).

Note that, since the time constant of the cooler127is relatively long, even when the cooling power decrease control of the cooler127is executed, the cooling power of the cooler127does not decrease rapidly but decreases gradually, as indicated by the solid line G2between time T7and time T8inFIG. 4B.

As indicated by the dotted line G1and the solid line G2between time T7and time T8inFIG. 4B, this enables the total amount of heat generation of the processors1of the respective computation nodes102to110to exceed the cooling power of the cooler127. That is, the total amount of heat generation of the processors1of the respective computation nodes102to110becomes excessive.

As a result, as indicated by the solid line G3between time T7and time T8inFIG. 4C, the temperature of the refrigerant circulating in the conduit121starts to increase. This prevents the refrigerant circulating in the conduit121from being excessively cooled.

When the temperature of the refrigerant circulating in the conduit121starts to increase, and the temperature T of the refrigerant detected by the temperature sensor122becomes equal to or more than the threshold value Th (see, e.g., time T8to time T12inFIG. 4C), the processor101aof the control node101resumes the process of causing the processor1of each of the computation nodes106to110to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) one by one at their respective timings between time T8and time T12(S26).

Subsequently, after all of the processors1of the respective computation nodes102to110are caused to transition to the power saving mode, the processor101aof the control node101executes the cooling power decrease control of the cooler127to decrease the cooling power of the cooler127to P1 that is the cooling power before time T1(S27).

Detail of First Embodiment

FIG. 6illustrates an example of the configuration of the control node101. The control node101includes the CPU101a(hereinafter also referred to as the processor101a), the main memory101b, a communication interface101cto which the computation nodes102to110, the cooler127, and the temperature sensor122are connected via the network NW, and a storage101dserving as an auxiliary storage apparatus. Although not illustrated, the processor101a, the main memory101b, the communication interface101c, and the storage101dare connected to each other via a bus or the like. An operating system (OS)101d1and the control program101d2are stored in the storage101d, and these programs are loaded into the main memory101b, and are executed by the processor101a. In addition, a node management table101d3is stored in the storage101d.

FIGS. 7A and 7Billustrate examples of the node management table101d3. Node IDs serving as identification information for identifying a plurality of the computation nodes102to110and the states of the processors1of the respective computation nodes102to110identified by the node IDs are associated with each other and are stored in the node management table101d3. The state of the processor1includes the non-power saving mode (job execution), the non-power saving mode (job non-execution), and the power saving mode (job non-execution). Every time the state of the processor1of each of the computation nodes102to110is changed, the processor101aof the control node101reflects the change in the node management table101d3. For example, in the case where the state of the processor1of the computation node102whose node ID is102is changed from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) when the state of the node management table101d3is a state illustrated inFIG. 7A, the processor101aof the control node101reflects the change in the node management table101d3, and the state of the node management table101d3is thereby changed to a state illustrated inFIG. 7B.

FIG. 8illustrates an example of the configuration of the computation node. The computation nodes102to110have the same configuration, and hence, hereinbelow, the configuration of the computation node102representing the other computation nodes will be mainly described. The computation node102includes the CPU1(hereinafter also referred to as the processor1), the main memory2, a communication interface3to which the control node101and the other computation nodes103to110are connected via the network NW, and a storage4serving as an auxiliary storage apparatus. Although not illustrated, the processor1, the main memory2, the communication interface3, and the storage4are connected to each other via a bus or the like. An operating system (OS)5and the job execution program6are stored in the storage4, and these programs are loaded into the main memory2, and are executed by the processor1.

FIG. 9is a view for illustrating the state of the processor1of each of the computation nodes102to110. In the case of the non-power saving mode (job execution), the processor1of each of the computation nodes102to110operates, e.g., with a power consumption of 140 to 200 W on a 3-GHz clock (an operating frequency of a processor). In the case of the non-power saving mode (job non-execution), the processor1of each of the computation nodes102to110operates, e.g., with a power consumption of 70 to 80 W on a 3-GHz clock (the operating frequency of the processor). In the case of the power saving mode (job non-execution), the processor1of each of the computation nodes102to110operates, e.g., with a power consumption of 20 W.

The processor101aof the control node101executes the control program101d2to cause the processor1of each of the computation nodes102to110to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution).

The power saving mode can be implemented by reducing the clock (the operating frequency of the processor) to a value lower than that of the clock in the non-power saving mode (job non-execution) (e.g., reducing the clock to 1.2 GHz from 3 GHz). In addition, in the case where the processor1of each of the computation nodes102to110includes a plurality of cores, the power saving mode can be implemented by turning off power supplied to the cores other than part of the cores (suspend mode). Further, the power saving mode can be implemented by limiting a bandwidth when the processor1accesses the main memory2. Furthermore, the power saving mode can be implemented by performing control to inhibit the processor1from using a single instruction multiple data (SIMD) command. The power saving mode can also be implemented by the other various methods. For example, the power saving mode can be implemented by appropriately combining the above methods.

FIG. 10illustrates an example of the configuration of the cooler127. The cooler127includes a chiller132that has a refrigerator and a pump (both not illustrated), a conduit129in which a refrigerant cooled by the chiller132circulates and that is cooled by the refrigerant, a valve130that controls the flow rate of the refrigerant circulating in the conduit129, and a heat exchanger131that cools the refrigerant in the conduit121by performing heat exchange between the conduit129and the conduit121.

The processor101aof the control node101executes the control program101d2to control the cooling power of the cooler127. For example, the processor101aof the control node101controls the cooling power of the cooler27stepwise by controlling the opening of the valve130such that, among a plurality of cooling powers obtained by dividing the range between the cooling power P1 watts and the cooling power P2 watts illustrated inFIG. 4B(e.g., the range therebetween is divided such that the number of resultant cooling powers matches the number of the computation nodes102to110), the cooler127has a specific cooling power. The cooling power of the cooler127may also be controlled stepwise by controlling the chiller132(controlling, e.g., the refrigeration power of the refrigerator or the speed of the pump).

FIG. 11is a flowchart for illustrating the cooling power control of the control program101d2in greater detail.

The processor101aof the control node101executes the control program101d2to perform the following process.

In the case where the job by the processor1of each of the computation nodes102to110is ended (S40), the processor101aof the control node101acquires the temperature of the refrigerant from the temperature sensor of the cooler127, and determines whether or not the acquired temperature T of the refrigerant is equal to or more than the threshold value Th (S41).

As a result, in the case where the temperature T of the refrigerant is equal to or more than the threshold value Th (S41: YES), the processor101aof the control node101selects one of the computation nodes in the non-power saving mode (job non-execution) by referring to the node management table101d3(S42), and changes the mode of the processor1of the selected computation node from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) (S34). The processor101aof the control node101then reflects the change in the node management table101d3.

On the other hand, as the result of the determination in S41, in the case where the temperature T of the refrigerant is less than the threshold value Th (S41: NO), the processor101aof the control node101executes the cooling power decrease control of the cooler127to decrease the cooling power of the cooler127by a predetermined extent (S44).

Next, the processor101aof the control node101determines whether or not all of the processors1of the respective computation nodes102to110in which the job is ended in S40are in the power saving mode by referring to the node management table101d3(S45).

As a result, in the case where all of the processors1of the respective computation nodes102to110in which the job is ended in S40are not in the power saving mode (S45: NO), the processor101aof the control node101waits a predetermined time period (S46).

Subsequently, the processor101aof the control node101repeatedly executes S40to S46described above until it is determined that all of the processors1of the respective computation nodes102to110in which the job is ended in S40are in the power saving mode in S45(S45: YES).

On the other hand, in S45, in the case where it is determined that all of the processors1of the respective computation nodes102to110in which the job is ended in S40are in the power saving mode (S45: YES), the processor101aof the control node101determines whether or not the cooling power of the cooler127is P1 watts that is the cooling power before time T1(S47).

As a result, in the case where the cooling power of the cooler127is not P1 watts (S47: NO), the processor101aof the control node101executes the cooling power decrease control of the cooler127to decrease the cooling power of the cooler127to P1 watts that is the cooling power before time T1(S48), and ends the process. On the other hand, in the case where the cooling power of the cooler127is P1 watts (S47: YES), the processor101aof the control node101ends the process.

As described thus far, according to the present embodiment, in the case where the temperature T of the refrigerant is less than the threshold value Th (S41: NO), the processor101aof the control node101executes the cooling power decrease control of the cooler127to decrease the cooling power by a predetermined extent (S44). On the other hand, in the case where the temperature T of the refrigerant is equal to or more than the threshold value Th (S41: YES), the processor101aof the control node101causes the processor1of each of a plurality of the computation nodes in which the execution of the job is ended to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) one by one at predetermined time intervals (S42, S43).

This enables the cooling power of the cooler127having the relatively long time constant (e.g., about several tens of minutes) and decreasing gradually to match (substantially match) the total amount of heat generation of the processors1of the respective computation nodes each having the relatively short time constant (e.g., about several seconds to several tens of seconds) and decreasing rapidly.

As a result, it is possible to cause the processor1of each of the computation nodes102to110to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) while preventing the refrigerant circulating in the conduit121from being excessively cooled. In addition, it is possible to prevent the above problem caused by the excessive cooling of the refrigerant circulating in the conduit121, i.e., the problem where the refrigerant is frozen and expanded, the conduit121is damaged, the refrigerant leaks from the damaged part, and peripheral electronic equipment fails.

Second Embodiment

FIG. 12is a view illustrating the schematic configuration of an information processing apparatus10A to which an information processing apparatus, a power saving transition program, and a power saving transition method of a second embodiment are applied. As illustrated inFIG. 12, in the information processing apparatus10A, a plurality of computation nodes111to119, a cooler128that cools a conduit123in which a refrigerant that cools the processors1(processor chips) of the plurality of computation nodes111to119circulates and the refrigerant in the conduit123, and a temperature sensor124that detects the temperature of the refrigerant (e.g., cooling water) circulating in the conduit123are added to the configuration of the information processing apparatus10of the first embodiment.

Similarly to the computation nodes102to110, each of the computation nodes111to119is a computer that includes the processor1and the main memory2.

The computation nodes111to119, the cooler128, and the temperature sensor124are connected to the control node101via the network NW.

FIG. 13illustrates an example of the node management table101d3used in the second embodiment. In the node management table101d3used in the second embodiment, cooler IDs for identifying the coolers127and128to which the computation nodes102to119identified by the node IDs belong are added to the node management table101d3used in the first embodiment that is illustrated inFIGS. 7A and 7B.

FIG. 14illustrates an example of the change of the state of the processor1of each of the computation nodes102to109correspondingly to the time axis.

An area A1_1hatched by a hatch H1_1inFIG. 14denotes that the state of each of the corresponding computation nodes102to104(processors1) is the non-power saving mode (first job execution).

In addition, an area A1_2hatched by a hatch H1_2inFIG. 14denotes that the state of each of the corresponding computation nodes105to109(processors1) is the non-power saving mode (second job execution).

Further, the area A2(a plurality of squares) hatched by the hatch H2inFIG. 14denotes that the state of the corresponding computation node (processor1) is the non-power saving mode (job non-execution).

Furthermore, the area A3hatched by the hatch H3inFIG. 14denotes that the state of the corresponding computation node (processor1) is the power saving mode (job non-execution).

As illustrated inFIG. 14, a job is not assigned to the processor1of each of the computation nodes102to104, and the processor1of each of the computation nodes102to104operates in the power saving mode (job non-execution) before time T1_2. A first job is assigned to the processor1of each of the computation nodes102to104by the control node101at time T1_2, and the processor1of each of the computation nodes102to104executes the first job between time T1_2and time T1_3, and ends the execution of the first job at time T1_3.

A job is not assigned to the processor1of each of the computation nodes105to119, and the processor1of each of the computation nodes105to119operates in the power saving mode (job non-execution) before time T1_1. A second job is assigned to the processor1of each of the computation nodes105to119by the control node101at time T1_1, and the processor1of each of the computation nodes105to119executes the second job between time T1_1and time T2, and ends the execution of the second job at time T2.

FIG. 15is a flowchart for illustrating the cooling power control of the control program101d2in detail.

The processor101aof the control node101executes the control program101d2to perform the following process.

Case where First Job is Ended

In the case where the first job by the computation nodes102to104is ended (S50), the processor101aof the control node101sets 0 in a cooler counter n for identifying the cooler (S51).

Next, the processor101aof the control node101acquires the temperature T of the refrigerant from the temperature sensor122of the cooler127identified by the cooler counter n (S52).

Next, the processor101aof the control node101determines whether or not the temperature T of the refrigerant acquired in S52is equal to or more than the threshold value Th (S53).

As a result, in the case where the temperature T of the refrigerant acquired in S52is equal to or more than the threshold value Th (S53: YES), the processor101aof the control node101selects one of the computation nodes in the non-power saving mode (job non-execution) belonging to the cooler127identified by the cooler counter n by referring to the node management table101d3(S54), and changes the mode of the processor1of the selected computation node from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) (S55). The processor101aof the control node101then reflects the change in the node management table101d3.

On the other hand, as the result of the determination in S53, in the case where the temperature T of the refrigerant acquired in S52is less than the threshold value Th (S53: NO), the control node101executes the cooling power decrease control of the cooler127to decrease the cooling power of the cooler127identified by the cooler counter n by a predetermined extent (S56).

Next, the processor101aof the control node101determines whether or not the processes of all of the coolers in which the first job is ended in S50are ended (S57).

Herein, the first job has been executed only in the computation nodes102to104belonging to the cooler127identified by the cooler counter n, and hence it is determined that the processes of all of the coolers in which the first job is ended in S50are ended (S57: YES).

Next, the processor101aof the control node101determines whether or not all of the computation nodes102to104in which the first job is ended in S50are in the power saving mode by referring to the node management table101d3(S58).

As a result, in the case where all of the computation nodes102to104in which the first job is ended in S50are not in the power saving mode (S58: NO), the processor101aof the control node101waits a predetermined time period (S59).

Subsequently, the processor101aof the control node101repeatedly executes S51to S59described above until it is determined that all of the computation nodes102to104in which the first job is ended in S50are in the power saving mode in S58(S58: YES).

On the other hand, in the case where it is determined that all of the computation nodes102to104in which the first job is ended in S50are in the power saving mode in S58(S58: YES), the processor101aof the control node101determines whether or not the cooling power of the cooler127is P1 watts that is the cooling power before time T1_2(S60).

As a result, in the case where the cooling power of the cooler127is not P1 watts that is the cooling power before time T1_2(S60: NO), the processor101aof the control node101decreases the cooling power of the cooler127to P1 watts that is the cooling power before time T1_2(S61), and ends the process. On the other hand, in the case where the cooling power of the cooler127is P1 watts that is the cooling power before time T1_2(S60: YES), the processor101aof the control node101ends the process.

Case where Second Job is Ended

In the case where the second job by the computation nodes105to119is ended (S50), the processor101aof the control node101sets 0 in the cooler counter n for identifying the cooler (S51).

Next, the processor101aof the control node101acquires the temperature T of the refrigerant from the temperature sensor122of the cooler127identified by the cooler counter n (S52).

Next, the processor101aof the control node101determines whether or not the temperature T of the refrigerant acquired in S52is equal to or more than the threshold value Th (S53).

As a result, in the case where the temperature T of the refrigerant acquired in S52is equal to or more than the threshold value Th (S53: YES), the processor101aof the control node101selects one of the computation nodes in the non-power saving mode (job non-execution) belonging to the cooler127identified by the cooler counter n by referring to the node management table101d3(S54), and changes the mode of the processor1of the selected computation node from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) (S55). The processor101aof the control node101then reflects the change in the node management table101d3.

On the other hand, as the result of the determination in S53, in the case where the temperature T of the refrigerant acquired in S52is less than the threshold value Th (S53: NO), the processor101aof the control node101executes the cooling power decrease control of the cooler127to decrease the cooling power of the cooler127identified by the cooler counter n by a predetermined extent (S56).

Next, the processor101aof the control node101determines whether or not the processes of all of the coolers in which the second job is ended in S50are ended (S57).

Herein, the second job is executed not only in the computation nodes105to110belonging to the cooler127identified by the cooler counter n but also in the computation nodes111to119belonging to the cooler128, and hence it is determined that the processes of all of the coolers in which the second job is ended in S50are not ended (S57: NO).

Next, the processor101aof the control node101increments the cooler counter n by 1 (S62).

Next, the processor101aof the control node101returns to S52, and acquires the temperature T of the refrigerant from the temperature sensor124of the cooler128identified by the cooler counter n (S52).

Next, the processor101aof the control node101determines whether or not the temperature T of the refrigerant acquired in S52is equal to or more than the threshold value Th (S53).

As a result, in the case where the temperature T of the refrigerant acquired in S52is equal to or more than the threshold value Th (S53: YES), the processor101aof the control node101selects one of the computation nodes in the non-power saving mode (job non-execution) belonging to the cooler128identified by the cooler counter n by referring to the node management table101d3(S54), and changes the mode of the processor1of the selected computation node102from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) (S55). The processor101aof the control node101then reflects the change in the node management table101d3.

On the other hand, as the result of the determination in S53, in the case where the temperature T of the refrigerant acquired in S52is less than the threshold value Th (S53: NO), the processor101aof the control node101executes the cooling power decrease control of the cooler128to decrease the cooling power of the cooler128identified by the cooler counter n by a predetermined extent (S56).

Next, the processor101aof the control node101determines whether or not the processes of all of the coolers in which the second job is ended in S50are ended (S57).

Herein, it is determined that the processes of both of the coolers127and128are ended (S57: YES).

Next, the processor101aof the control node101determines whether or not all of the computation nodes105to119in which the second job is ended in S50are in the power saving mode by referring to the node management table101d3(S58).

As a result, in the case where all of the computation nodes105to119in which the second job is ended in S50are not in the power saving mode (S58: NO), the processor101aof the control node101waits a predetermined time period (S59).

Subsequently, the processor101aof the control node101repeatedly executes S51to S59and S62described above until it is determined that all of the computation nodes105to119in which the second job is ended in S50are in the power saving mode in S58(S58: YES).

On the other hand, in the case where it is determined that all of the computation nodes105to119in which the second job is ended in S50are in the power saving mode in S58(S58: YES), the processor101aof the control node101determines whether or not the cooling power of each of the coolers127and128is P1 watts that is the cooling power before time T1_2(S60).

As a result, in the case where the cooling power of each of the coolers127and128is not P1 watts that is the cooling power before time T1_2(S60: NO), the processor101aof the control node101decreases the cooling power of each of the coolers127and128to P1 watts that is the cooling power before time T1_2(S61), and ends the process. On the other hand, in the case where the cooling power of each of the coolers127and128is P1 watts that is the cooling power before time T1_2(S60: YES), the processor101aof the control node101ends the process.

As described thus far, according to the present embodiment, in the case where the temperature T of the refrigerant is less than the threshold value Th (S53: NO), the processor101aof the control node101executes the cooling power decrease control of each of the coolers127and128to decrease the cooling power by a predetermined extent (S56). On the other hand, in the case where the temperature T of the refrigerant is equal to or more than the threshold value Th (S53: YES), the processor101aof the control node101causes the processor1of each of a plurality of the computation nodes in which the execution of the job is ended to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) one by one at predetermined time intervals (S54, S55).

This enables the cooling power of each of the coolers127and128each having the relatively long time constant (e.g., about several tens of minutes) and decreasing gradually to match (substantially match) the total amount of heat generation of the computation nodes each having the relatively short time constant (e.g., about several seconds to several tens of seconds) and decreasing rapidly.

As a result, it is possible to cause the processor1of each of the computation nodes102to119to transition from the non-power saving mode (job non-execution) to the power saving mode (job non-execution) while preventing the refrigerants circulating in the conduits121and123from being excessively cooled. In addition, it is possible to prevent the above problem caused by the excessive cooling of the refrigerants circulating in the conduits121and123, i.e., the problem where the refrigerants are frozen and expand, the conduits121and123are damaged, the refrigerants leak from the damaged parts, and peripheral electronic equipment fails.

Third Embodiment

In the case where a new third job is submitted at time T5(seeFIG. 18) after the end of the second job, the new third job is normally assigned to any computation node in which the job is not executed.

However, when the new third job is assigned to the computation node having transitioned to the power saving mode, the temperature of the computation node is excessively increased until the cooling power catches up with the total amount of heat generation of the processor1of the computation node that executes the newly assigned third job in the non-power saving mode.

To cope with this, in a third embodiment, in the case where the new third job is submitted, frequency of excessive increase of the temperature of the computation node is reduced by executing a process (hereinafter also referred to as a job preferential assignment process) of assigning the job preferentially to the computation node not in the power saving mode but in the non-power saving mode (job non-execution).

Hereinbelow, as the third embodiment, a description will be given of a process (hereinafter also referred to as the job preferential assignment process) in which, as illustrated inFIG. 18, in the case where a user submits the new third job, e.g., at time T5after the end of the second job in the information processing apparatus10A of the second embodiment, the control node101assigns the submitted third job preferentially to a non-power saving mode (job non-execution).

Case where Computation Nodes102to119are Directly Connected (Case of Direct Network)

FIG. 16is a flowchart for illustrating the job preferential assignment process in the case where the computation nodes102to119are directly connected (in the case of a direct network).FIG. 17illustrates the image of the direct network. InFIG. 17, a plurality of squares represent computation nodes (processors1). Note that, for easier understanding of the description,FIG. 17depicts squares (computation nodes (processors1)) larger in number than the computation nodes102to109. An area AA (a plurality of squares) hatched by a hatch HA inFIG. 17denotes that the state of the corresponding computation node (processor1) is the non-power saving mode (job non-execution). In addition, an area BB (a plurality of squares) hatched by a hatch HB denotes that the state of the corresponding computation node (processor1) is the power saving mode (job non-execution).

In the case where a user specifies a job shape and submits a job (S70), the processor101aof the control node101assigns 0 to a variable max_neco (S71). The area AA (a plurality of squares) hatched by the hatch HA inFIG. 17is an example of the job shape.

Next, the processor101aof the control node101retrieves available nodes in a submitted job shape that have not yet been retrieved (S72).

Next, the processor101aof the control node101determines whether or not the available nodes in the submitted job shape are retrieved (S73).

As a result, in the case where the available nodes are not retrieved (S73: NO), the processor101aof the control node101waits for the end of the job that is being executed, and executes S71to S73again.

On the other hand, as the result of the determination in S73, in the case where the available nodes are retrieved (S73: YES), the processor101aof the control node101assigns the number of, among the retrieved available nodes, computation nodes in the non-power saving mode to a variable n (S75).

Next, the processor101aof the control node101determines whether or not the variable n>=variable max_neco is satisfied (S76).

As a result, in the case where the variable n>=variable max_neco is satisfied (S76: YES), the processor101aof the control node101records the position of the detected available node (non-power saving mode) (S77). The processor101arecords the position thereof in, e.g., a variable PN.

Next, the processor101aof the control node101assigns the content of the variable n to the variable max_neco (S78).

Next, the processor101aof the control node101determines whether or not all of the available nodes are retrieved (S79).

As a result, in the case where all of the available nodes are retrieved (S79: YES), the processor101aof the control node101assigns the job to the nodes (computation nodes) recorded in the variable PN (S80).

On the other hand, as the result of the determination in S79, in the case where all of the available node are not retrieved (S79: NO), the processor101aof the control node101repeatedly executes S72to S79until all of the available nodes are retrieved (S79: YES).

It is possible to retrieve the available nodes in the submitted job shape with the larger number of the non-power saving modes by using S76to S78, and hence it is possible to assign the job to more computation nodes in the non-power saving mode.

For example, as illustrated inFIG. 18, in the case where the new third job is submitted at time T5, it is possible to assign the job to more computation nodes in the non-power saving mode in an area A4_2hatched by a hatch H4_2than in an area A4_1hatched by a hatch H4_1. In this case, the processor101aof the control node101assigns the third job not to the computation nodes104to110corresponding to the area A4_1but to the computation nodes113to119corresponding to the area A4_2.FIG. 18is a view for illustrating the computation node to which the new third job is assigned in the case where the new third job is submitted at time T5.

As described above, according to the process inFIG. 16, in the case where the new third job is submitted at time T5(seeFIG. 18) after the end of the second job, it is possible to assign the new third job to more computation nodes in the non-power saving mode. Consequently, it is possible to reduce the frequency of excessive increase of the temperature of the computation node.

Case where Computation Nodes102to119are Indirectly Connected (Case of Indirect Network)

FIG. 19is a flowchart for illustrating the job preferential assignment process in the case where the computation nodes102to109are connected indirectly via a switch (not illustrated) (the case of an indirect network).

In the case where the user submits a job (S90), the processor101aof the control node101assigns 0 to the variable n (S91).

Next, the processor101aof the control node101retrieves the available node in the non-power saving mode (S92).

Next, the processor101aof the control node101determines whether or not the available node in the non-power saving mode is retrieved (S93).

As a result, in the case where the available node is not retrieved (S93: NO), the processor101aof the control node101selects the available node in the power saving mode (S94), and adds the selected available node to a list (S95).

On the other hand, as the result of the determination in S93, in the case where the available node in the non-power saving mode is retrieved (S93: YES), the processor101aof the control node101adds the retrieved available node in the non-power saving mode to the list (S96).

Next, the processor101aof the control node101increments the variable n by 1 (S97).

Next, the processor101aof the control node101determines whether or not the variable n matches the number of nodes requested by the job (S98).

As a result, in the case where the variable n matches the number of nodes requested by the job (S98: YES), the processor101aof the control node101assigns the job to the node recorded in the list (S99).

On the other hand, in the case where the variable n does not match the number of nodes requested by the job (S98: NO), the processor101aof the control node101repeatedly executes S92to S98until the variable n matches the number of nodes requested by the job (S98: YES).

According to the present process, it is possible to assign the job submitted in S90preferentially to the available node in the non-power saving mode retrieved in S93.

For example, as illustrated inFIG. 20, in the case where the new third job is submitted at time T5, the processor101aof the control node101can assign the third job preferentially to the computation nodes108to110and113to116in the non-power saving mode (job non-execution).FIG. 20is a view for illustrating the computation node to which the new third job is assigned in the case where the new third job is submitted at time T5.

As described above, according to the process inFIG. 19, in the case where the new third job is submitted at time T5(seeFIG. 20) after the end of the second job, it is possible to assign the new third job to more computation nodes in the non-power saving mode (job non-execution). Consequently, it is possible to reduce the frequency of excessive increase of the temperature of the computation node.