Commit-ID: 7c177d994eb9637302b79e80d331f48dfbe26368 Gitweb: http://git.kernel.org/tip/7c177d994eb9637302b79e80d331f48dfbe26368 Author: Jason Low <jason.l...@hp.com> AuthorDate: Wed, 14 Oct 2015 12:07:53 -0700 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Thu, 15 Oct 2015 11:23:41 +0200
posix_cpu_timer: Optimize fastpath_timer_check() In fastpath_timer_check(), the task_cputime() function is always called to compute the utime and stime values. However, this is not necessary if there are no per-thread timers to check for. This patch modifies the code such that we compute the task_cputime values only when there are per-thread timers set. Signed-off-by: Jason Low <jason.l...@hp.com> Reviewed-by: Oleg Nesterov <o...@redhat.com> Reviewed-by: Frederic Weisbecker <fweis...@gmail.com> Reviewed-by: Davidlohr Bueso <d...@stgolabs.net> Reviewed-by: George Spelvin <li...@horizon.com> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com> Cc: Steven Rostedt <rost...@goodmis.org> Cc: hideaki.kim...@hpe.com Cc: terry.r...@hpe.com Cc: scott.nor...@hpe.com Cc: Peter Zijlstra <pet...@infradead.org> Link: http://lkml.kernel.org/r/1444849677-29330-2-git-send-email-jason.l...@hp.com Signed-off-by: Thomas Gleixner <t...@linutronix.de> --- kernel/time/posix-cpu-timers.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 892e3da..aa4b6f4 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -1117,17 +1117,12 @@ static inline int task_cputime_expired(const struct task_cputime *sample, static inline int fastpath_timer_check(struct task_struct *tsk) { struct signal_struct *sig; - cputime_t utime, stime; - - task_cputime(tsk, &utime, &stime); if (!task_cputime_zero(&tsk->cputime_expires)) { - struct task_cputime task_sample = { - .utime = utime, - .stime = stime, - .sum_exec_runtime = tsk->se.sum_exec_runtime - }; + struct task_cputime task_sample; + task_cputime(tsk, &task_sample.utime, &task_sample.stime); + task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime; if (task_cputime_expired(&task_sample, &tsk->cputime_expires)) return 1; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
