Merge remote-tracking branch 'scsi/for-next'

[deliverable/linux.git] / kernel / sched / cputime.c

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index a846cf89eb96182950db834207322c92722d0d2e..b93c72d5f64fc686df20d78889f11c6a01bc920a 100644 (file)
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -306,6 +306,26 @@ static inline cputime_t account_other_time(cputime_t max)
        return accounted;
 }
 
+#ifdef CONFIG_64BIT
+static inline u64 read_sum_exec_runtime(struct task_struct *t)
+{
+       return t->se.sum_exec_runtime;
+}
+#else
+static u64 read_sum_exec_runtime(struct task_struct *t)
+{
+       u64 ns;
+       struct rq_flags rf;
+       struct rq *rq;
+
+       rq = task_rq_lock(t, &rf);
+       ns = t->se.sum_exec_runtime;
+       task_rq_unlock(rq, t, &rf);
+
+       return ns;
+}
+#endif
+
 /*
  * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
  * tasks (sum on group iteration) belonging to @tsk's group.
@@ -318,6 +338,17 @@ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
        unsigned int seq, nextseq;
        unsigned long flags;
 
+       /*
+        * Update current task runtime to account pending time since last
+        * scheduler action or thread_group_cputime() call. This thread group
+        * might have other running tasks on different CPUs, but updating
+        * their runtime can affect syscall performance, so we skip account
+        * those pending times and rely only on values updated on tick or
+        * other scheduler action.
+        */
+       if (same_thread_group(current, tsk))
+               (void) task_sched_runtime(current);
+
        rcu_read_lock();
        /* Attempt a lockless read on the first round. */
        nextseq = 0;
@@ -332,7 +363,7 @@ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
                        task_cputime(t, &utime, &stime);
                        times->utime += utime;
                        times->stime += stime;
-                       times->sum_exec_runtime += task_sched_runtime(t);
+                       times->sum_exec_runtime += read_sum_exec_runtime(t);
                }
                /* If lockless access failed, take the lock. */
                nextseq = 1;