1 /*
2 * Copyright 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "Thread.h"
18
19 #include <sched.h>
20 #include <unistd.h>
21
22 namespace samples {
23
getNumCpus()24 int32_t getNumCpus() {
25 static int32_t sNumCpus = []() {
26 pid_t pid = gettid();
27 cpu_set_t cpuSet;
28 CPU_ZERO(&cpuSet);
29 sched_getaffinity(pid, sizeof(cpuSet), &cpuSet);
30
31 int32_t numCpus = 0;
32 while (CPU_ISSET(numCpus, &cpuSet)) {
33 ++numCpus;
34 }
35
36 return numCpus;
37 }();
38
39 return sNumCpus;
40 }
41
setAffinity(int32_t cpu)42 void setAffinity(int32_t cpu) {
43 cpu_set_t cpuSet;
44 CPU_ZERO(&cpuSet);
45 CPU_SET(cpu, &cpuSet);
46 sched_setaffinity(gettid(), sizeof(cpuSet), &cpuSet);
47 }
48
setAffinity(Affinity affinity)49 void setAffinity(Affinity affinity) {
50 const int32_t numCpus = getNumCpus();
51
52 cpu_set_t cpuSet;
53 CPU_ZERO(&cpuSet);
54 for (int32_t cpu = 0; cpu < numCpus; ++cpu) {
55 switch (affinity) {
56 case Affinity::None:
57 CPU_SET(cpu, &cpuSet);
58 break;
59 case Affinity::Even:
60 if (cpu % 2 == 0) CPU_SET(cpu, &cpuSet);
61 break;
62 case Affinity::Odd:
63 if (cpu % 2 == 1) CPU_SET(cpu, &cpuSet);
64 break;
65 }
66 }
67
68 sched_setaffinity(gettid(), sizeof(cpuSet), &cpuSet);
69 }
70
71 } // namespace samples {
72