1 /*
2 * Copyright (C) 2021 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 <stdlib.h>
18 #include <sys/syscall.h>
19 #include <unistd.h>
20
21 #include <iostream>
22
usage(int exit_status)23 [[noreturn]] static void usage(int exit_status) {
24 std::cerr << "Usage: " << getprogname() << " <tid> <uclamp_min> <uclamp_max>" << std::endl
25 << " tid Thread ID to apply the uclamp setting." << std::endl
26 << " uclamp_min uclamp.min value range from [0, 1024]." << std::endl
27 << " uclamp_max uclamp.max value range from [0, 1024]." << std::endl;
28 exit(exit_status);
29 }
30
31 struct sched_attr {
32 __u32 size;
33 __u32 sched_policy;
34 __u64 sched_flags;
35 __s32 sched_nice;
36 __u32 sched_priority;
37 __u64 sched_runtime;
38 __u64 sched_deadline;
39 __u64 sched_period;
40 __u32 sched_util_min;
41 __u32 sched_util_max;
42 };
43
sched_setattr(int pid,struct sched_attr * attr,unsigned int flags)44 static int sched_setattr(int pid, struct sched_attr* attr, unsigned int flags) {
45 return syscall(__NR_sched_setattr, pid, attr, flags);
46 }
47
set_uclamp(int32_t min,int32_t max,int tid)48 static int set_uclamp(int32_t min, int32_t max, int tid) {
49 sched_attr attr = {};
50 attr.size = sizeof(attr);
51
52 attr.sched_flags = (SCHED_FLAG_KEEP_ALL | SCHED_FLAG_UTIL_CLAMP);
53 attr.sched_util_min = min;
54 attr.sched_util_max = max;
55
56 int ret = sched_setattr(tid, &attr, 0);
57 if (ret) {
58 int err = errno;
59 std::cerr << "sched_setattr failed for thread " << tid << " err=" << err << std::endl;
60 }
61
62 return ret;
63 }
64
main(int argc,char * argv[])65 int main(int argc, char* argv[]) {
66 if (argc != 4) {
67 usage(EXIT_FAILURE);
68 }
69
70 int tid = atoi(argv[1]);
71 int uclamp_min = atoi(argv[2]);
72 int uclamp_max = atoi(argv[3]);
73
74 return set_uclamp(uclamp_min, uclamp_max, tid);
75 }
76