sched_setaffinity - phpMan

SCHED_SETAFFINITY(2)       Linux Programmer’s Manual      SCHED_SETAFFINITY(2)



NAME
       sched_setaffinity, sched_getaffinity - set and get a process’s CPU affinity mask

SYNOPSIS
       #include <sched.h>

       int sched_setaffinity(pid_t pid, unsigned int len, unsigned long *mask);

       int sched_getaffinity(pid_t pid, unsigned int len, unsigned long *mask);


DESCRIPTION
       sched_setaffinity sets the CPU affinity mask of the process denoted by pid.  If pid
       is zero, then the current process is used.

       The affinity mask is represented by the bitmask stored in mask.  The least signifi-
       cant bit corresponds to the first logical processor number on the system, while the
       most significant bit corresponds to the last logical processor number on  the  sys-
       tem.   A set bit corresponds to a legally schedulable CPU while an unset bit corre-
       sponds to an illegally schedulable CPU.  In other words, a process is bound to  and
       will  only  run on processors whose corresponding bit is set.  Usually, all bits in
       the mask are set.

       The argument len is the length of the data pointed to by mask.   Normally  this  is
       the  size  of  a word on the system.  For compatibility with future versions of the
       Linux kernel, since this size can change, the bitmask supplied must be at least  as
       large as the affinity mask stored in the kernel.

       The  function  sched_getaffinity  writes  into the pointer supplied by mask that is
       size len the affinity mask of process pid.  If pid is zero, then the  mask  of  the
       current process is returned.


RETURN VALUE
       On success, sched_setaffinity and sched_getaffinity both return 0.  On error, -1 is
       returned, and errno is set appropriately.


ERRORS
       EFAULT A supplied memory address was invalid.

       ESRCH  The process whose ID is pid could not be found.

       EPERM  The calling process does not have appropriate privileges. The process  call-
              ing sched_setaffinity needs an effective uid equal to the euid or uid of the
              process identified by pid, or it must possess the CAP_SYS_NICE capability.

       EINVAL The affinity bitmask mask contains no processors that are physically on  the
              system  or the length len is smaller than the size of the affinity mask used
              by the kernel.

HISTORY
       The affinity syscalls were introduced in Linux kernel  2.5.8.   The  library  calls
       were  introduced  in  glibc  2.3,  and  are still in glibc 2.3.2. Later glibc 2.3.2
       development versions changed this interface to one without the len field, and still
       later versions reverted again. The glibc prototype is now

       /* Set the CPU affinity for a task */
       extern int sched_setaffinity (pid_t pid, size_t cpusetsize,
                                     const cpu_set_t *cpuset);

       /* Get the CPU affinity for a task */
       extern int sched_getaffinity (pid_t pid, size_t cpusetsize,
                                     cpu_set_t *cpuset);

SEE ALSO
       sched_setscheduler(2),       sched_getscheduler(2),      sched_get_priority_max(2),
       sched_get_priority_min(2), nice(2), setpriority(2), getpriority(2),

       sched_setscheduler(2) has a description of the Linux scheduling scheme.



Linux                             2004-04-22              SCHED_SETAFFINITY(2)

Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache/1.3.41 (Unix) PHP/5.2.5 mod_perl/1.30 mod_gzip/1.3.26.1a
Under GNU General Public License
2009-01-10 11:09 @38.103.63.58 CrawledBy CCBot/1.0 (+http://www.commoncrawl.org/bot.html)