Abstract:
The present invention has been conceived in view of the above described situation, and an object of the invention is to provide an information processing device, data transfer method and information storage medium that can commence data transfer to an I/O device immediately, and can stably exhibit data transfer performance. In an information processing device provided with hardware for sharing an address translation table, for translating logical addresses of a memory to physical addresses, between a main processor and a sub-processor, one of the sub-processors is caused to function as means for receiving a transfer request designating a logical address of the memory, means for translating the logical address that has been designated in the transfer request to a physical address using the shared address translation table, and means for executing transfer processing for data stored in the memory  14  according to the translated physical address.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an information processing device, a data transfer method, and an information storage medium. 
     In the event of a processor transferring data in a main memory to an I/O device such as an NIC (Network Interface Card), if the processor is already executing another program, there is a potential problem that it will not be possible to demonstrate sufficient transfer performance such as latency and transfer rate. It has therefore, been considered to provide dedicated hardware for data transfer at the I/O device side, so that it is made possible to stably exhibit transfer performance. 
     However, in order for the above-described dedicated hardware to directly access data in the main memory, it is necessary for an address translation table, for translating the logical address of the data to a physical address, to be set beforehand. With the above-described structure therefore, it is necessary to create a new address translation table in the dedicated hardware before data transfer, and there is a problem in that it is not possible to execute data transfer immediately as the need arises. 
     SUMMARY OF THE INVENTION 
     The present invention has been conceived in view of the above-described situation, and an object of the invention is to provide an information processing device, data transfer method and information storage medium that can commence data transfer to an I/O device immediately, and can stably exhibit data transfer performance. 
     In order to solve the above described problems, an information processing device of the present invention comprises a memory, a main processor, at least one sub-processor, an I/O device, and address translation table sharing means, for sharing an address translation table, for translating logical addresses of the memory to physical addresses, between the main processor and the at least one sub-processor, wherein the one sub-processors is provided with request receiving means for receiving a transfer request designating a logical address of the memory, address translation means for translating the logical address designated by the transfer request to a physical address using the shared address translation table, and transfer process execution means for executing transfer process for data stored in the memory to the I/O device in accordance with the translated physical address. 
     It is also possible for the one sub-processor to be provided with a local memory. In this case, it is possible for the transfer process execution means to include means for reading out data from the physical address translated by the address translation means, and storing data in the local memory based on the data, and means for sending a transfer request designating the physical address of data stored in the local memory to the I/O device, and for the I/O device to read out data from the local memory in accordance with a physical address designated by the transfer request received from the one sub processor. 
     Also, a data transfer method of the present invention is performed by a computer comprising a memory, a main processor, at least one sub-processor, an I/O device, and address translation table sharing means, for sharing an address translation table, for translating logical addresses of the memory to physical addresses, between the main processor and the at least one sub-processor, and executes, in the one sub-processor, a step of receiving a transfer request designating a logical address of the memory, a step of translating the logical address designated by the transfer request to a physical address using the shared address translation table, and a step of executing a transfer process for data stored in the memory in accordance with the translated physical address. 
     Also, an information storage medium of the resent invention stores a program, executed by a computer comprising a memory, a main processor, at least one sub-processor, an I/O device, and address translation table sharing means, for sharing an address translation table, for translating logical addresses of the memory to physical addresses, between the main processor and the at least one sub-processor, and the program cause the at least one sub-processor to function as means for receiving a transfer request designating a logical address of the memory, means for translating the logical address designated by the transfer request to a physical address using the shared address translation table, and means for executing a transfer process for data stored in the memory in accordance with the translated physical address. This program can be stored in an information storage medium capable of being read by various types of computer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a structural drawing of an information processing device of one embodiment of the present invention. 
         FIG. 2  is a drawing showing stored content of the local memory and the main memory. 
         FIG. 3  is a sequence drawing showing a data transfer process. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     One embodiment of the present invention will be described in the following based on the drawings. 
       FIG. 1  is a structural drawing of an information processing device of the present invention. As shown in  FIG. 1 , this information processing device  10  includes a main processor  12  and a plurality of sub-processors  24 - 1  to  24 -n, and is constructed as an asymmetric multi-core processor. The main processor  12  and the plurality of sub-processors  24 - 1  to  24 -n are all connected to a bus  22 , and data can be mutually sent and received among the processors via this bus  22 . A main memory  14  is connected to the bus  22  via a memory interface  16 , and an NIC  20  as an I/O device is connected to the bus  22  via an input output interface  18 . 
     The main processor  12  is program execution means for executing programs, such as an operating system and performing task allocation to the sub-processors  24 - 1  to  24 -n, and contains a memory management unit  12   a  and a cache memory  12   b . The memory management unit  12   a  is hardware for executing processing for translating a logical address, that is generated by the main processor  12  or received externally, into a physical address of the main memory  14  and carries out this translation processing in accordance with an address translation table stored in the main memory  14 . The address translation table is a table which associates logical addresses with physical addresses, and is made up of page groups of a specified size such as 4 KB. Therefore, the memory management section  12   a  is provided with a memory for storing the necessary pages, of these pages, and when a logical address generated by the main processor  12  does not exist in a page stored in the memory, another page is read out from the main memory  14  and the memory contents updated. Also, the cache memory  12   b  is a memory for temporarily storing commands and data to be processed by the main processor  12 . 
     The sub-processors  24  ( 24 - 1  to  24 -n) are ancillary program execution means containing local memory  24   a , a memory management section  24   b  and a DMAC (Direct Memory Access Controller). The local memory  24   a , as shown in  FIG. 2(   a ) is used to store a program  24   a ′ executed by the sub processor  24 , and temporarily stored data that is the object of processing. The memory control section  24   b  also provides the same functions as the memory management section  12   a . More specifically, the memory management unit  24   b  is hardware for executing processing for translating a logical address, that is generated by the sub processor  24  or received externally, into a physical address of the main memory  14  and carries out this translation processing in accordance with an address translation table stored in the main memory  14 . The memory management section  24   b  is provided with a memory for storing the necessary pages of the address translation table, and when a logical address that requires translation does not exist in a page stored in the memory, another page is read out from the main memory  14  and the memory contents updated. The DMAC  24   c  is also a control unit for direct access to the main memory  14 , without going via the main processor  12 . With this embodiment, in particular, of the sub-processors  24 - 1  to  24 -n, a transfer task for transferring transfer data stored in the main memory  14  to the NIC  20  is allocated to the sub-processor  24 - 1 , and in this way it is possible to execute high speed data transfer without imposing a processing load on the main processor  12 . Therefore, processing to transfer the transfer data stored in the main memory  14  to the NIC  20  is implemented by storing a data transfer program in the local memory  24   a - 1  as a sub-processor program  24   a ′, and having the sub-processor  24 - 1  execute this data transfer program. Also, at the time of this transfer task, as shown in  FIG. 2(   a ), data to be transferred to the NIC  20  that is stored in the main memory  14 , that is, transfer data  24   a ″, is temporarily stored in the local memory  24   a - 1  of the sib-processor  24 - 1  (described in detail later). 
     As shown in  FIG. 2(   b ), a system program  14   a , such as an OS (operating system) executed by the main processor  12 , a user program  14   b  executed by the main processor  12 , and an address translation table  14   c  are stored in the main memory  14 . The address translation table  14   c  is updated by the main processor system program  14   a , and when the table has been updated this fact is also notified to the sub-processors  24 - 1  to  24 -n, and the latest address translation table  14   c  is shared by the main processor  12  and the sub-processors  24 - 1  to  24 -n. Data generated by the main processor  12  and the sub-processors  24 - 1  to  24 -n that is to be transferred to the NIC  20 , namely transfer data  14   d , is also stored in the main memory  14 . As has been described above, this transfer data  14   d  is temporarily transferred to the sub-processor  24 - 1  at the time of transfer to the NIC  20 , and is stored in the local memory  24   a - 1 . 
     The NIC  20  is an interface for connecting this information processing device  10  to a data communication network such as a LAN (Local Area Network), and contains a DMAC  20   a  and a buffer memory  20   b . The DMAC  20   a  is a control unit for direct access to the main memory  14  and the local memory  24   a  of each sub-processor  24 , and stores received data in the buffer memory  20   b . The buffer memory  2   b  is a FIFO (First In First Out) buffer, and data stored in the buffer memory  20   b  are sequentially sent to the network. 
     Here, data transfer processing of the information processing device  10  will be described.  FIG. 3  is a sequence diagram for data transfer processing when data transfer to the sub-processor  24 - 1 , which is a processor for data transfer, is carried out after transfer data  14   d  has been stored in the main memory  14  by a sub-processor N. As shown in  FIG. 3 , if a data transfer request designating of logical address (here made “a”) of transfer data  14   d  is transmitted by the sub-processor  24 -n via the bus  22  to the sub-processor  24 - 1  (S 101 ), the sub-processor  24 - 1  receives this data transfer request. The memory management section  24   b - 1  of the sub-processor  24 - 1  translates the logical address “a” designated in the data transfer request to a physical address “A” based on some pages of the address translation table  14   c  stored in the internal memory (S 102 ). This physical address “A” is then transmitted to the memory interface  16  (S 103 ), and transfer data  14   d  stored at the physical address “A” of the main memory  14  is received (S 104 ). Next, the sub-processor  24 - 1  stores the received transfer data  14   d  in the local memory  24   a - 1  (S 105 ). Then, a data transfer instruction designating a physical address (here made “B”) for a storage destination is transmitted via the bus  22  to the NIC  20  (S 106 ). The NIC  20  transits the physical address “B” to the sub-processor  24 - 1  in response to this instruction (S 107 ), and receives transfer data  24   a ″ (namely transfer data  14   d ) returned from the sub -processor  24 - 1  (S 108 ). The thus received transfer data  24   a ″ is then stored in the buffer memory  20   b  and used in communication processing (S 109 ). 
     According to the above described information processing device  10 , since a single sub -processor  24 - 1  constituting a multi-core processor is allocated solely to data transfer, it is possible to implement data transfer at high speed and with low latency regardless of the operating state of the main processor  12 . Also, since data transfer is implemented using an address translation table  14   c  that is shared between the main processor  12  and the sub -processor  24  due to the hardware architecture of the information processing device  10 , it is possible to carry out data transfer immediately as the need arises. 
     Incidentally, the present invention is not limited to the above described embodiment, and various modifications are possible. For example, with the above described embodiment an NIC  20  has been adopted as the I/O device, but it is also possible to have another I/O device such as a hard disk storage device. Also, with the above described embodiment transfer data  14   d  stored in the main memory is stored as it is in the local memory  24   a - 1  of the sub-processor  24 - 1 , but it is also possible, for example, to perform various translation processes such as encryption in the sub-processor  24 - 1 , and after that store as transfer data  24   a ″, and transfer this translated data  24   a ″ to the NIC  20 .