fg_affinity.c File Reference

CPU affinity routines used by Flowgrind. More...

#include "config.h"
#include <stdbool.h>
#include <errno.h>
#include <unistd.h>
#include "fg_affinity.h"

Go to the source code of this file.

Functions
int	get_ncores (enum ncore_query query)
	Return either the total number of configured or available cores. More...
int	pthread_getaffinity (pthread_t thread, unsigned *core)
	Returns the CPU affinity of thread thread in the buffer pointed to by core. More...
int	pthread_setaffinity (pthread_t thread, unsigned core)
	Set CPU affinity of the thread thread to the core core. More...

Detailed Description

CPU affinity routines used by Flowgrind.

Definition in file fg_affinity.c.

Function Documentation

get_ncores()

int get_ncores

(

enum ncore_query

query

)

Return either the total number of configured or available cores.

Parameters

[in]

query

indicates if either the configured or available cores should be be returned

See also

enum nproc_query

Returns

return number of processors on success, or -1 for failure

Definition at line 56 of file fg_affinity.c.

{
        switch (query) {
        case NCORE_CONFIG:
                /* processors configured */
                return (int)sysconf(_SC_NPROCESSORS_CONF);
                break;
        case NCORE_CURRENT:
                /* processors available */
                return (int)sysconf(_SC_NPROCESSORS_ONLN);
                break;
        default:
                errno = EINVAL;
                return -1;
        }
}

pthread_getaffinity()

int pthread_getaffinity	(	pthread_t	thread,
		unsigned *	core
	)

Returns the CPU affinity of thread thread in the buffer pointed to by core.

Parameters

[in]	thread	thread ID
[out]	core	core to which thread thread is bounded

Returns

return 0 for success, or -1 for failure

Definition at line 85 of file fg_affinity.c.

{
        cpu_set_t cpuset;
        int rc = pthread_getaffinity_np(thread, sizeof(cpu_set_t), &cpuset);
        if (rc)
                return -1;
 
        /* If the cpuset contains only one CPU, then that's the answer. For
         * all other cpuset contents, we treat the binding as unknown */
        core = NULL;
        bool core_found = false;
        for (unsigned i = 0; i < CPU_SETSIZE; i++) {
                if (CPU_ISSET(i, &cpuset)) {
                        if (!core_found) {
                                core_found = true;
                                *core = i;
                        } else {
                                core_found = false;
                                core = NULL;
                                break;
                        }
                }
        }
 
        return (core_found ? 0 : -1);
}

pthread_setaffinity()

int pthread_setaffinity	(	pthread_t	thread,
		unsigned	core
	)

Set CPU affinity of the thread thread to the core core.

Parameters

[in]	thread	thread ID
[in]	core	core to which thread thread will be bounded

Returns

return 0 for success, or -1 for failure

Definition at line 75 of file fg_affinity.c.

{
        cpu_set_t cpuset;
        CPU_ZERO(&cpuset);
        CPU_SET(core, &cpuset);
 
        int rc = pthread_setaffinity_np(thread, sizeof(cpu_set_t), &cpuset);
        return (rc == 0 ? 0 : -1);
}