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#include "types.hh"
#include "util.hh"
#include "affinity.hh"
#if __linux__
#include <sched.h>
#endif
namespace nix {
#if __linux__
static bool didSaveAffinity = false;
static cpu_set_t savedAffinity;
std::ostream& operator<<(std::ostream &os, const cpu_set_t &cset)
{
auto count = CPU_COUNT(&cset);
for (int i=0; i < count; ++i)
{
os << (CPU_ISSET(i,&cset) ? "1" : "0");
}
return os;
}
#endif
void setAffinityTo(int cpu)
{
#if __linux__
if (sched_getaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1) return;
didSaveAffinity = true;
debug(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)
printError("failed to lock thread to CPU %1%", 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)
{
std::ostringstream oss;
oss << savedAffinity;
printError("failed to restore CPU affinity %1%", oss.str());
}
#endif
}
}
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