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| .TH PTHREAD_ATTR_SETAFFINITY_NP 3 2017-09-15 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| pthread_attr_setaffinity_np, pthread_attr_getaffinity_np \- set/get |
| CPU affinity attribute in thread attributes object |
| .SH SYNOPSIS |
| .nf |
| .BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */" |
| .B #include <pthread.h> |
| .PP |
| .BI "int pthread_attr_setaffinity_np(pthread_attr_t *" attr , |
| .BI " size_t " cpusetsize ", const cpu_set_t *" cpuset ); |
| .BI "int pthread_attr_getaffinity_np(const pthread_attr_t *" attr , |
| .BI " size_t " cpusetsize ", cpu_set_t *" cpuset ); |
| .PP |
| Compile and link with \fI\-pthread\fP. |
| .fi |
| .SH DESCRIPTION |
| The |
| .BR pthread_attr_setaffinity_np () |
| function |
| sets the CPU affinity mask attribute of the |
| thread attributes object referred to by |
| .I attr |
| to the value specified in |
| .IR cpuset . |
| This attribute determines the CPU affinity mask |
| of a thread created using the thread attributes object |
| .IR attr . |
| .PP |
| The |
| .BR pthread_attr_getaffinity_np () |
| function |
| returns the CPU affinity mask attribute of the thread attributes object |
| referred to by |
| .IR attr |
| in the buffer pointed to by |
| .IR cpuset . |
| .PP |
| The argument |
| .I cpusetsize |
| is the length (in bytes) of the buffer pointed to by |
| .IR cpuset . |
| Typically, this argument would be specified as |
| .IR sizeof(cpu_set_t) . |
| .PP |
| For more details on CPU affinity masks, see |
| .BR sched_setaffinity (2). |
| For a description of a set of macros |
| that can be used to manipulate and inspect CPU sets, see |
| .BR CPU_SET (3). |
| .SH RETURN VALUE |
| On success, these functions return 0; |
| on error, they return a nonzero error number. |
| .SH ERRORS |
| .TP |
| .BR EINVAL |
| .RB ( pthread_attr_setaffinity_np ()) |
| .I cpuset |
| specified a CPU that was outside the set supported by the kernel. |
| (The kernel configuration option |
| .BR CONFIG_NR_CPUS |
| defines the range of the set supported by the kernel data type |
| .\" cpumask_t |
| used to represent CPU sets.) |
| .\" The raw sched_getaffinity() system call returns the size (in bytes) |
| .\" of the cpumask_t type. |
| .TP |
| .B EINVAL |
| .RB ( pthread_attr_getaffinity_np ()) |
| A CPU in the affinity mask of the thread attributes object referred to by |
| .I attr |
| lies outside the range specified by |
| .IR cpusetsize |
| (i.e., |
| .IR cpuset / cpusetsize |
| is too small). |
| .TP |
| .B ENOMEM |
| .RB ( pthread_attr_setaffinity_np ()) |
| Could not allocate memory. |
| .SH VERSIONS |
| These functions are provided by glibc since version 2.3.4. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .TS |
| allbox; |
| lbw30 lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR pthread_attr_setaffinity_np (), |
| .BR pthread_attr_getaffinity_np () |
| T} Thread safety MT-Safe |
| .TE |
| .sp 1 |
| .SH CONFORMING TO |
| These functions are nonstandard GNU extensions; |
| hence the suffix "_np" (nonportable) in the names. |
| .SH NOTES |
| In glibc 2.3.3 only, |
| versions of these functions were provided that did not have a |
| .I cpusetsize |
| argument. |
| Instead the CPU set size given to the underlying system calls was always |
| .IR sizeof(cpu_set_t) . |
| .SH SEE ALSO |
| .BR sched_setaffinity (2), |
| .BR pthread_attr_init (3), |
| .BR pthread_setaffinity_np (3), |
| .BR cpuset (7), |
| .BR pthreads (7) |