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#include "libutil/affinity.hh"
#include <glog/logging.h>
#include "libutil/types.hh"
#include "libutil/util.hh"
#if __linux__
#include <sched.h>
#endif
namespace nix {
#if __linux__
static bool didSaveAffinity = false;
static cpu_set_t savedAffinity;
#endif
void setAffinityTo(int cpu) {
#if __linux__
if (sched_getaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1) {
return;
}
didSaveAffinity = true;
DLOG(INFO) << "locking this thread to CPU " << cpu;
cpu_set_t newAffinity;
CPU_ZERO(&newAffinity);
CPU_SET(cpu, &newAffinity);
if (sched_setaffinity(0, sizeof(cpu_set_t), &newAffinity) == -1) {
LOG(ERROR) << "failed to lock thread to CPU " << cpu;
}
#endif
}
int lockToCurrentCPU() {
#if __linux__
int cpu = sched_getcpu();
if (cpu != -1) {
setAffinityTo(cpu);
}
return cpu;
#else
return -1;
#endif
}
void restoreAffinity() {
#if __linux__
if (!didSaveAffinity) {
return;
}
if (sched_setaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1) {
LOG(ERROR) << "failed to restore affinity";
}
#endif
}
} // namespace nix
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