1/*
2 * Copyright 2012 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef _GNU_SOURCE
9#define _GNU_SOURCE //for pthread_setaffinity_np
10#endif
11
12#include "SkThreadUtils.h"
13#include "SkThreadUtils_pthread.h"
14
15#include <pthread.h>
16
17static int nth_set_cpu(unsigned int n, cpu_set_t* cpuSet) {
18    n %= CPU_COUNT(cpuSet);
19    for (unsigned int setCpusSeen = 0, currentCpu = 0; true; ++currentCpu) {
20        if (CPU_ISSET(currentCpu, cpuSet)) {
21            ++setCpusSeen;
22            if (setCpusSeen > n) {
23                return currentCpu;
24            }
25        }
26    }
27}
28
29bool SkThread::setProcessorAffinity(unsigned int processor) {
30    SkThread_PThreadData* pthreadData = static_cast<SkThread_PThreadData*>(fData);
31    if (!pthreadData->fValidPThread) {
32        return false;
33    }
34
35    cpu_set_t parentCpuset;
36    if (0 != pthread_getaffinity_np(pthread_self(), sizeof(cpu_set_t), &parentCpuset)) {
37        return false;
38    }
39
40    cpu_set_t cpuset;
41    CPU_ZERO(&cpuset);
42    CPU_SET(nth_set_cpu(processor, &parentCpuset), &cpuset);
43    return 0 == pthread_setaffinity_np(pthreadData->fPThread,
44                                       sizeof(cpu_set_t),
45                                       &cpuset);
46}
47