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Change set_sched_policy to set slack for current thread.

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Change set_sched_policy to use prctl PR_SET_TIMERSLACK if setting the policy
for the current thread and /proc/<tid>/timerslack_ns is not supported by the
kernel.

Bug: 32972117
Test: Verified that libcutils SchedPolicy tests pass.  See details in
testing done comment in
https://android-review.googlesource.com/381303 .
Change-Id: Id70940ed7f9ed94c3d105213f069bf3e5a8d8824
This commit is contained in:
Erik Staats 2017-04-26 15:15:55 -07:00
parent 1ac29896b0
commit d32331fb27
1 changed files with 19 additions and 13 deletions
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32
libcutils/sched_policy.cpp
View file

@ -343,16 +343,25 @@ int set_cpuset_policy(int tid, SchedPolicy policy)
static void set_timerslack_ns(int tid, unsigned long long slack) {
// v4.6+ kernels support the /proc/<tid>/timerslack_ns interface.
// TODO: once we've backported this, log if the open(2) fails.
char buf[64];
snprintf(buf, sizeof(buf), "/proc/%d/timerslack_ns", tid);
int fd = open(buf, O_WRONLY | O_CLOEXEC);
if (fd != -1) {
int len = snprintf(buf, sizeof(buf), "%llu", slack);
if (write(fd, buf, len) != len) {
SLOGE("set_timerslack_ns write failed: %s\n", strerror(errno));
if (__sys_supports_timerslack) {
char buf[64];
snprintf(buf, sizeof(buf), "/proc/%d/timerslack_ns", tid);
int fd = open(buf, O_WRONLY | O_CLOEXEC);
if (fd != -1) {
int len = snprintf(buf, sizeof(buf), "%llu", slack);
if (write(fd, buf, len) != len) {
SLOGE("set_timerslack_ns write failed: %s\n", strerror(errno));
}
close(fd);
return;
}
}
// TODO: Remove when /proc/<tid>/timerslack_ns interface is backported.
if ((tid == 0) || (tid == gettid())) {
if (prctl(PR_SET_TIMERSLACK, slack) == -1) {
SLOGE("set_timerslack_ns prctl failed: %s\n", strerror(errno));
}
close(fd);
return;
}
}
@ -431,10 +440,7 @@ int set_sched_policy(int tid, SchedPolicy policy)
}
if (__sys_supports_timerslack) {
set_timerslack_ns(tid, policy == SP_BACKGROUND ?
TIMER_SLACK_BG : TIMER_SLACK_FG);
}
set_timerslack_ns(tid, policy == SP_BACKGROUND ? TIMER_SLACK_BG : TIMER_SLACK_FG);
return 0;
}