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Commit d32331fb authored by Erik Staats's avatar Erik Staats
Browse files

Change set_sched_policy to set slack for current thread. 

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
parent 1ac29896

libcutils/sched_policy.cpp

+19 −13
Original line number Diff line number Diff line
@@ -343,6 +343,7 @@ 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.

    if (__sys_supports_timerslack) {

        char buf[64];

        snprintf(buf, sizeof(buf), "/proc/%d/timerslack_ns", tid);

        int fd = open(buf, O_WRONLY | O_CLOEXEC);
@@ -356,6 +357,14 @@ static void set_timerslack_ns(int tid, unsigned long long slack) { 
        }

    }



    // 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));

        }

    }

}



int set_sched_policy(int tid, SchedPolicy policy)

{

    if (tid == 0) {
@@ -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;

}