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### OSIdleTime[​](#osidletime "Direct link to OSIdleTime")

The ratio of time the CPU core was idle (not even ready to run a process waiting for IO) from the OS kernel standpoint. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. This does not include the time when the CPU was under-utilized due to the reasons internal to the CPU (memory loads, pipeline stalls, branch mispredictions, running another SMT core). The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSIdleTimeCPU\_*N*[​](#osidletimecpu_n "Direct link to osidletimecpu_n")

The ratio of time the CPU core was idle (not even ready to run a process waiting for IO) from the OS kernel standpoint. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. This does not include the time when the CPU was under-utilized due to the reasons internal to the CPU (memory loads, pipeline stalls, branch mispredictions, running another SMT core). The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSIdleTimeNormalized[​](#osidletimenormalized "Direct link to OSIdleTimeNormalized")

The value is similar to `OSIdleTime` but divided to the number of CPU cores to be measured in the [0..1] interval regardless of the number of cores. This allows you to average the values of this metric across multiple servers in a cluster even if the number of cores is non-uniform, and still get the average resource utilization metric. If specified, the Cgroup CPU quota divided by its period can be used instead of the actual number of CPU cores, and in that case the value of this metric may exceed 1 at some moments.

### OSInterrupts[​](#osinterrupts "Direct link to OSInterrupts")

The number of interrupts on the host machine. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### OSIrqTime[​](#osirqtime "Direct link to OSIrqTime")

The ratio of time spent for running hardware interrupt requests on the CPU. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. A high number of this metric may indicate hardware misconfiguration or a very high network load. The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSIrqTimeCPU\_*N*[​](#osirqtimecpu_n "Direct link to osirqtimecpu_n")

The ratio of time spent for running hardware interrupt requests on the CPU. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. A high number of this metric may indicate hardware misconfiguration or a very high network load. The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSIrqTimeNormalized[​](#osirqtimenormalized "Direct link to OSIrqTimeNormalized")

The value is similar to `OSIrqTime` but divided to the number of CPU cores to be measured in the [0..1] interval regardless of the number of cores. This allows you to average the values of this metric across multiple servers in a cluster even if the number of cores is non-uniform, and still get the average resource utilization metric. If specified, the Cgroup CPU quota divided by its period can be used instead of the actual number of CPU cores, and in that case the value of this metric may exceed 1 at some moments.

### OSMemoryAvailable[​](#osmemoryavailable "Direct link to OSMemoryAvailable")

The amount of memory available to be used by programs, in bytes. This is very similar to the `OSMemoryFreePlusCached` metric. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### OSMemoryBuffers[​](#osmemorybuffers "Direct link to OSMemoryBuffers")

The amount of memory used by OS kernel buffers, in bytes. This should be typically small, and large values may indicate a misconfiguration of the OS. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### OSMemoryCached[​](#osmemorycached "Direct link to OSMemoryCached")

The amount of memory used by the OS page cache, in bytes. Typically, almost all available memory is used by the OS page cache - high values of this metric are normal and expected. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### OSMemoryFreePlusCached[​](#osmemoryfreepluscached "Direct link to OSMemoryFreePlusCached")

The amount of free memory plus OS page cache memory on the host system, in bytes. This memory is available to be used by programs. The value should be very similar to `OSMemoryAvailable`. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### OSMemoryFreeWithoutCached[​](#osmemoryfreewithoutcached "Direct link to OSMemoryFreeWithoutCached")

The amount of free memory on the host system, in bytes. This does not include the memory used by the OS page cache memory, in bytes. The page cache memory is also available for usage by programs, so the value of this metric can be confusing. See the `OSMemoryAvailable` metric instead. For convenience, we also provide the `OSMemoryFreePlusCached` metric, that should be somewhat similar to OSMemoryAvailable. See also <https://www.linuxatemyram.com/>. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### OSMemoryTotal[​](#osmemorytotal "Direct link to OSMemoryTotal")

The total amount of memory on the host system, in bytes.

### OSNiceTime[​](#osnicetime "Direct link to OSNiceTime")

The ratio of time the CPU core was running userspace code with higher priority. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSNiceTimeCPU\_*N*[​](#osnicetimecpu_n "Direct link to osnicetimecpu_n")

The ratio of time the CPU core was running userspace code with higher priority. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSNiceTimeNormalized[​](#osnicetimenormalized "Direct link to OSNiceTimeNormalized")

The value is similar to `OSNiceTime` but divided to the number of CPU cores to be measured in the [0..1] interval regardless of the number of cores. This allows you to average the values of this metric across multiple servers in a cluster even if the number of cores is non-uniform, and still get the average resource utilization metric. If specified, the Cgroup CPU quota divided by its period can be used instead of the actual number of CPU cores, and in that case the value of this metric may exceed 1 at some moments.

### OSOpenFiles[​](#osopenfiles "Direct link to OSOpenFiles")

The total number of opened files on the host machine. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### OSProcessesBlocked[​](#osprocessesblocked "Direct link to OSProcessesBlocked")

Number of threads blocked waiting for I/O to complete (`man procfs`). This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### OSProcessesCreated[​](#osprocessescreated "Direct link to OSProcessesCreated")

The number of processes created. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### OSProcessesRunning[​](#osprocessesrunning "Direct link to OSProcessesRunning")