File Coverage

lib/Sys/CpuAffinity.xs

Criterion	Covered	Total	%
statement	30	39	76.9
branch	30	48	62.5
condition			n/a
subroutine			n/a
pod			n/a
total	60	87	68.9

#include
#include
#include
#include
#include




=pod

linux-sched_getaffinity.xs: return CPU affinity with the Linux
sched_getaffinity(2)  system call. See also:
linux-sched_setaffinity.xs .


/*
 * This declaration isn't used and looks useless. But for some
 * reason I don't understand at all, for some versions of perl
 * with some build configurations running on some systems,
 * this declaration is the difference between XS code that works
 * (specifically, passing t/11-exercise-all.t) and code that
 * segfaults. For the same reason, the  cpu_set_t  variables
 * in  xs_sched_getaffinity_get_affinity()  below are declared
 * static .
 *
 * Any insights into this issue would be profoundly appreciated.
 */

=cut

char ___linux_sched_getaffinity_dummy[4096];

void diag()
{
  fprintf(stderr,"---\n");
  fprintf(stderr,"diag CPU_SETSIZE=%d\n", CPU_SETSIZE);
  fprintf(stderr,"diag sizeof(__cpu_mask)=%d\n", (int) sizeof(__cpu_mask));
  fprintf(stderr,"diag __NCPUBITS=%d\n", (int) __NCPUBITS);
  fprintf(stderr,"diag sizeof(cpu_set_t)=%d\n", (int) sizeof(cpu_set_t));
  fprintf(stderr,"diag sizeof(pid_t)=%d\n", (int) sizeof(pid_t));
}




=pod

linux-sched_setaffinity.xs: update CPU affinity with the Linux
sched_setaffinity(2)  system call. See also:
linux-sched_getaffinity.xs .

=cut




MODULE = Sys::CpuAffinity        PACKAGE = Sys::CpuAffinity

int
xs_fortytwo()
  CODE:
    /* The purpose of this trivial code snippet is to
       see whether you can compile something, anything,
       during this build process.

       If this doesn't compile, then you probably don't have
       a compiler or it is badly misconfigured, and you
       won't be able to generate any XS code with this
       distribution. This would not necessarily mean that
       this module wouldn't work -- it may still be possible
       to manipulate CPU affinities on your system with Pure
       Perl calls or with external utilities available on
       your system.

       If this is the ONLY thing that compiles, then your
       system-specific snippets might be incorrect, or your
       system might be obscure enough that no system-specific
       snippets have been developed for it yet. */
    RETVAL = 42;
  OUTPUT:
    RETVAL








int
xs_sched_getaffinity_get_affinity(pid,maskarray,debug_flag)
	int pid
        AV *maskarray
	int debug_flag
  CODE:
    int i, z;
    int r = 0;
    int ncpus = __NCPUBITS;
    static cpu_set_t _set2, *_set1;

    if(debug_flag) diag();
    if(debug_flag) fprintf(stderr,"getaffinity0\n");
    _set1 = &_set2;
    if(debug_flag) {
      fprintf(stderr,"getaffinity1 pid=%d size=%d %d ncpu=%d cpuset=%p %d\n",
              (int) pid, (int) CPU_SETSIZE, (int) sizeof(cpu_set_t),
              ncpus, (void *) _set1, ncpus);
    }
    /* RT 94560: CPU_SETSIZE might be less than sizeof(cpu_set_t) ? */
    z = sched_getaffinity((pid_t) pid, sizeof(cpu_set_t), _set1);
#ifdef CPU_COUNT
    /* CPU_COUNT() can undercount the number of cpus? And __NCPUBITS can
     * overcount. I don't know if there's any harm in that.
     */
#endif
    if(debug_flag) fprintf(stderr,"getaffinity2 ncpus=%d\n", ncpus);
    if (z) {
      if(debug_flag) fprintf(stderr,"getaffinity3 z=%d err=%d\n", z, errno);
      r = 0;
    } else {
      int nn = ncpus * 4;
      if (nn > __NCPUBITS) nn = __NCPUBITS;

      av_clear(maskarray);
      if(debug_flag) fprintf(stderr,"getaffinity5\n");
      /* tests.reproducible-builds.org/debian/rb-pkg/unstable/i386/
         libsys-cpuaffinity-perl.html:
             __NCPUBITS=32 but taskset,/proc/cpuinfo say there are 34 cpus */
      for (i = 0, r = 0; i < nn; i++) {
        if(debug_flag) fprintf(stderr,"getaffinity6 i=%d r=%d\n", i, r);
        if (CPU_ISSET(i, &_set2)) {
          r |= 1;
          av_push(maskarray, newSViv(i));
          if(debug_flag) fprintf(stderr,"getaffinity8 add %d to mask\n", i);
        }
      }
      if(debug_flag) fprintf(stderr,"getaffinitya r=%d\n",r);
    }
    RETVAL = r;
  OUTPUT:
    RETVAL





int
xs_sched_setaffinity_set_affinity(pid,mask,debug_flag)
    int pid
    AV *mask
    int debug_flag
  CODE:
    static cpu_set_t cpumask;
    int i,r;

    CPU_ZERO(&cpumask);
    for (i=0; i <= av_len(mask); i++) {
        int c = SvIV(*av_fetch(mask,i,0));
        if (debug_flag) fprintf(stderr,"sched_setaffinity%d = %d\n", i, c);
        CPU_SET(c, &cpumask);
    }
    r = sched_setaffinity(pid, sizeof(cpu_set_t), &cpumask);
    if (debug_flag) fprintf(stderr,"sched_setaffinity(%d,%d,...) = %d\n", pid, sizeof(cpu_set_t), r);
    if (r != 0) {
      fprintf(stderr,"result: %d %d %s\n", r, errno,
            errno==EFAULT ? "EFAULT" /* a supplied memory address was invalid */
          : errno==EINVAL ? "EINVAL" /* the affinity bitmask contains no
                                        processors that are physically on the
                                        system, or _cpusetsize_ is smaller than
                                        the size of the affinity mask used by
                                        the kernel */
          : errno==EPERM ? "EPERM"   /* the calling process does not have
                                        appropriate privilieges. The process
                                        calling *sched_setaffinity()* needs an
                                        effective user ID equal to the user ID
                                        or effective user ID of the process
                                        identified by _pid_, or it must possess
                                        the _CAP_SYS_NICE_ capability. */
          : errno==ESRCH ? "ESRCH"   /* the process whose ID is _pid_ could not
                                        be found */
              :"E_WTF");
    }
    RETVAL = !r;
  OUTPUT:
    RETVAL