66 lines
1.9 KiB
C++
66 lines
1.9 KiB
C++
// Copyright 2016 Google Inc. All rights reserved
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build ignore
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#include "affinity.h"
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#include "flags.h"
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#include "log.h"
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#ifdef __linux__
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#include <random>
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#include <sched.h>
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#include <sys/types.h>
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#include <unistd.h>
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void SetAffinityForSingleThread() {
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cpu_set_t cs;
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CPU_ZERO(&cs);
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std::default_random_engine generator(getpid());
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std::uniform_int_distribution<int> distribution(0,g_flags.num_cpus-1);
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int cpu = distribution(generator);
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// Try to come up with a CPU and one close to it. This should work on most
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// hyperthreaded system, but may be less optimal under stranger setups.
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// Choosing two completely different CPUs would work here as well, it's just a
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// couple percent faster if they're close (and still faster than letting the
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// scheduler do whatever it wants).
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cpu = cpu - (cpu % 2);
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CPU_SET(cpu, &cs);
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if (g_flags.num_cpus > 1)
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CPU_SET(cpu+1, &cs);
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if (sched_setaffinity(0, sizeof(cs), &cs) < 0)
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WARN("sched_setaffinity: %s", strerror(errno));
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}
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void SetAffinityForMultiThread() {
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cpu_set_t cs;
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CPU_ZERO(&cs);
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for (int i = 0; i < g_flags.num_cpus; i++) {
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CPU_SET(i, &cs);
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}
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if (sched_setaffinity(0, sizeof(cs), &cs) < 0)
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WARN("sched_setaffinity: %s", strerror(errno));
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}
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#else
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void SetAffinityForSingleThread() {}
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void SetAffinityForMultiThread() {}
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#endif
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