NVML API Reference Guide (PDF) - vR470 (older) - Last updated July 29, 2021 - Send Feedback

2.14.1. CPU and Memory Affinity

[Device Queries]

This chapter describes NVML operations that are associated with CPU and memory affinity.

Defines

#define NVML_AFFINITY_SCOPE_NODE 0
Scope of NUMA node for affinity queries.
#define NVML_AFFINITY_SCOPE_SOCKET 1
Scope of processor socket for affinity queries.

Functions

nvmlReturn_t nvmlDeviceClearCpuAffinity ( nvmlDevice_t device )
nvmlReturn_t nvmlDeviceGetCpuAffinity ( nvmlDevice_t device, unsigned int  cpuSetSize, unsignedlong* cpuSet )
nvmlReturn_t nvmlDeviceGetCpuAffinityWithinScope ( nvmlDevice_t device, unsigned int  cpuSetSize, unsignedlong* cpuSet, nvmlAffinityScope_t scope )
nvmlReturn_t nvmlDeviceGetMemoryAffinity ( nvmlDevice_t device, unsigned int  nodeSetSize, unsignedlong* nodeSet, nvmlAffinityScope_t scope )
nvmlReturn_t nvmlDeviceSetCpuAffinity ( nvmlDevice_t device )

Defines

#define NVML_AFFINITY_SCOPE_NODE 0

#define NVML_AFFINITY_SCOPE_SOCKET 1

Functions

nvmlReturn_t nvmlDeviceClearCpuAffinity ( nvmlDevice_t device )
Parameters
device
The identifier of the target device
Returns

Description

Clear all affinity bindings for the calling thread. Note, this is a change as of version 8.0 as older versions cleared the affinity for a calling process and all children.

For Kepler or newer fully supported devices. Supported on Linux only.

nvmlReturn_t nvmlDeviceGetCpuAffinity ( nvmlDevice_t device, unsigned int  cpuSetSize, unsignedlong* cpuSet )
Parameters
device
The identifier of the target device
cpuSetSize
The size of the cpuSet array that is safe to access
cpuSet
Array reference in which to return a bitmask of CPUs, 64 CPUs per unsigned long on 64-bit machines, 32 on 32-bit machines
Returns

Description

Retrieves an array of unsigned ints (sized to cpuSetSize) of bitmasks with the ideal CPU affinity for the device For example, if processors 0, 1, 32, and 33 are ideal for the device and cpuSetSize == 2, result[0] = 0x3, result[1] = 0x3 This is equivalent to calling nvmlDeviceGetCpuAffinityWithinScope with NVML_AFFINITY_SCOPE_NODE.

For Kepler or newer fully supported devices. Supported on Linux only.

nvmlReturn_t nvmlDeviceGetCpuAffinityWithinScope ( nvmlDevice_t device, unsigned int  cpuSetSize, unsignedlong* cpuSet, nvmlAffinityScope_t scope )
Parameters
device
The identifier of the target device
cpuSetSize
The size of the cpuSet array that is safe to access
cpuSet
Array reference in which to return a bitmask of CPUs, 64 CPUs per unsigned long on 64-bit machines, 32 on 32-bit machines
scope
Scope that change the default behavior
Returns

Description

Retrieves an array of unsigned ints (sized to cpuSetSize) of bitmasks with the ideal CPU affinity within node or socket for the device. For example, if processors 0, 1, 32, and 33 are ideal for the device and cpuSetSize == 2, result[0] = 0x3, result[1] = 0x3

Note:

If requested scope is not applicable to the target topology, the API will fall back to reporting the CPU affinity for the immediate non-I/O ancestor of the device.

For Kepler or newer fully supported devices. Supported on Linux only.

nvmlReturn_t nvmlDeviceGetMemoryAffinity ( nvmlDevice_t device, unsigned int  nodeSetSize, unsignedlong* nodeSet, nvmlAffinityScope_t scope )
Parameters
device
The identifier of the target device
nodeSetSize
The size of the nodeSet array that is safe to access
nodeSet
Array reference in which to return a bitmask of NODEs, 64 NODEs per unsigned long on 64-bit machines, 32 on 32-bit machines
scope
Scope that change the default behavior
Returns

Description

Retrieves an array of unsigned ints (sized to nodeSetSize) of bitmasks with the ideal memory affinity within node or socket for the device. For example, if NUMA node 0, 1 are ideal within the socket for the device and nodeSetSize == 1, result[0] = 0x3

Note:

If requested scope is not applicable to the target topology, the API will fall back to reporting the memory affinity for the immediate non-I/O ancestor of the device.

For Kepler or newer fully supported devices. Supported on Linux only.

nvmlReturn_t nvmlDeviceSetCpuAffinity ( nvmlDevice_t device )
Parameters
device
The identifier of the target device
Returns

Description

Sets the ideal affinity for the calling thread and device using the guidelines given in nvmlDeviceGetCpuAffinity(). Note, this is a change as of version 8.0. Older versions set the affinity for a calling process and all children. Currently supports up to 1024 processors.

For Kepler or newer fully supported devices. Supported on Linux only.


NVML API Reference Guide (PDF) - vR470 (older) - Last updated July 29, 2021 - Send Feedback