55 lines
1.1 KiB
C++
55 lines
1.1 KiB
C++
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#include "types.hh"
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#include "util.hh"
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#include "affinity.hh"
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#if HAVE_SCHED_H
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#include <sched.h>
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#endif
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namespace nix {
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static bool didSaveAffinity = false;
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static cpu_set_t savedAffinity;
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void setAffinityTo(int cpu)
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{
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#if HAVE_SCHED_SETAFFINITY
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if (sched_getaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1) return;
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didSaveAffinity = true;
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printMsg(lvlDebug, format("locking this thread to CPU %1%") % cpu);
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cpu_set_t newAffinity;
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CPU_ZERO(&newAffinity);
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CPU_SET(cpu, &newAffinity);
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if (sched_setaffinity(0, sizeof(cpu_set_t), &newAffinity) == -1)
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printMsg(lvlError, format("failed to lock thread to CPU %1%") % cpu);
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#endif
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}
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int lockToCurrentCPU()
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{
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#if HAVE_SCHED_SETAFFINITY
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if (getEnv("NIX_AFFINITY_HACK", "1") == "1") {
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int cpu = sched_getcpu();
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if (cpu != -1) setAffinityTo(cpu);
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return cpu;
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}
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#endif
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return -1;
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}
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void restoreAffinity()
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{
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#if HAVE_SCHED_SETAFFINITY
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if (!didSaveAffinity) return;
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if (sched_setaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1)
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printMsg(lvlError, "failed to restore affinity %1%");
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#endif
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}
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}
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