#include "types.hh"
#include "util.hh"
#include "affinity.hh"

#if HAVE_SCHED_H
#include <sched.h>
#endif

namespace nix {


#if HAVE_SCHED_SETAFFINITY
static bool didSaveAffinity = false;
static cpu_set_t savedAffinity;
#endif


void setAffinityTo(int cpu)
{
#if HAVE_SCHED_SETAFFINITY
    if (sched_getaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1) return;
    didSaveAffinity = true;
    printMsg(lvlDebug, format("locking this thread to CPU %1%") % cpu);
    cpu_set_t newAffinity;
    CPU_ZERO(&newAffinity);
    CPU_SET(cpu, &newAffinity);
    if (sched_setaffinity(0, sizeof(cpu_set_t), &newAffinity) == -1)
        printMsg(lvlError, format("failed to lock thread to CPU %1%") % cpu);
#endif
}


int lockToCurrentCPU()
{
#if HAVE_SCHED_SETAFFINITY
    int cpu = sched_getcpu();
    if (cpu != -1) setAffinityTo(cpu);
    return cpu;
#else
    return -1;
#endif
}


void restoreAffinity()
{
#if HAVE_SCHED_SETAFFINITY
    if (!didSaveAffinity) return;
    if (sched_setaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1)
        printMsg(lvlError, "failed to restore affinity %1%");
#endif
}


}
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<div class='path'>path: <a href='/guix/log/?id=cf4a0c1f67003146057597363f06bb0056687e0f'>root</a>/<a href='/guix/log/gnu?id=cf4a0c1f67003146057597363f06bb0056687e0f'>gnu</a>/<a href='/guix/log/gnu/tests?id=cf4a0c1f67003146057597363f06bb0056687e0f'>tests</a>/<a href='/guix/log/gnu/tests/audio.scm?id=cf4a0c1f67003146057597363f06bb0056687e0f'>audio.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/tests/audio.scm?id=cf4a0c1f67003146057597363f06bb0056687e0f&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-11-06 23:14:14 +0100'>2020-11-06</span></td><td><a href='/guix/commit/gnu/tests/audio.scm?id=9909eddbc55c6cac5acccab453993cd113aa38a1'>tests: mpd: Remove race condition; use default MPD configuration.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>