ath10k: add trace event for WMI_DEBUG_MESG_EVENTID

[cascardo/linux.git] / kernel / sched / core.c

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1deccd7..c180860 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2253,6 +2253,20 @@ unsigned long long task_sched_runtime(struct task_struct *p)
        struct rq *rq;
        u64 ns = 0;
 
+#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
+       /*
+        * 64-bit doesn't need locks to atomically read a 64bit value.
+        * So we have a optimization chance when the task's delta_exec is 0.
+        * Reading ->on_cpu is racy, but this is ok.
+        *
+        * If we race with it leaving cpu, we'll take a lock. So we're correct.
+        * If we race with it entering cpu, unaccounted time is 0. This is
+        * indistinguishable from the read occurring a few cycles earlier.
+        */
+       if (!p->on_cpu)
+               return p->se.sum_exec_runtime;
+#endif
+
        rq = task_rq_lock(p, &flags);
        ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
        task_rq_unlock(rq, p, &flags);