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| author | Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> | 2015-11-19 16:47:29 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-12-04 10:34:43 +0100 |
| commit | 7877a0ba5ec63c7b0111b06c773f1696fa17b35a (patch) | |
| tree | d4f8158b6f4b96f26f85eb76b686eb0be4aa2cd0 /kernel/sched/cputime.c | |
| parent | ad936d8658fd348338cb7d42c577dac77892b074 (diff) | |
| download | linux-7877a0ba5ec63c7b0111b06c773f1696fa17b35a.tar.bz2 | |
sched/cputime: Remove extra cost in task_cputime()
There is an extra cost in task_cputime() and task_cputime_scaled() when
nohz_full is not activated. When vtime accounting is not enabled, we
don't need to get deltas of utime and stime under vtime seqlock.
This patch removes that cost with adding a shortcut route if vtime
accounting is not enabled.
Use context_tracking_is_enabled() to check if vtime is accounting on
some cpu, in which case only we need to check the tickless cputime delta.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1447948054-28668-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/cputime.c')
| -rw-r--r-- | kernel/sched/cputime.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 05de80b48586..1128d4ba6c55 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -853,6 +853,14 @@ void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime) { cputime_t udelta, sdelta; + if (!context_tracking_is_enabled()) { + if (utime) + *utime = t->utime; + if (stime) + *stime = t->stime; + return; + } + fetch_task_cputime(t, utime, stime, &t->utime, &t->stime, &udelta, &sdelta); if (utime) @@ -866,6 +874,14 @@ void task_cputime_scaled(struct task_struct *t, { cputime_t udelta, sdelta; + if (!context_tracking_is_enabled()) { + if (utimescaled) + *utimescaled = t->utimescaled; + if (stimescaled) + *stimescaled = t->stimescaled; + return; + } + fetch_task_cputime(t, utimescaled, stimescaled, &t->utimescaled, &t->stimescaled, &udelta, &sdelta); if (utimescaled) |