Groups > linux.kernel > #1201085

Re: [RFC PATCH] timer: Improve itimers scalability

From	Jason Low <jason.low2@hp.com>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH] timer: Improve itimers scalability
Date	2015-08-05 22:00 +0200
Message-ID	<pUd10-2OG-7@gated-at.bofh.it> (permalink)
References	<pTUUp-1Rq-13@gated-at.bofh.it> <pU3kZ-5J6-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, 2015-08-05 at 11:37 +0200, Peter Zijlstra wrote:
> On Tue, Aug 04, 2015 at 05:29:44PM -0700, Jason Low wrote:
> 
> > @@ -1137,6 +1148,13 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
> >  	if (READ_ONCE(sig->cputimer.running)) {
> 
> Maybe make that:
> 
> 	if (READ_ONCE(sig->cputimer.running) &&
> 	    !READ_ONCE(sig->cputimer.is_checking_timer)) {

Yes, I think it would be better if the check is done here.

And perhaps the comment can be modified to:

/*
 * Check if thread group timers expired. This is skipped if the cputimer
 * is not running or if another thread in the group is already checking
 * for thread group cputimers.
 */

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Thread

[RFC PATCH] timer: Improve itimers scalability Jason Low <jason.low2@hp.com> - 2015-08-05 02:40 +0200
  Re: [RFC PATCH] timer: Improve itimers scalability Peter Zijlstra <peterz@infradead.org> - 2015-08-05 11:30 +0200
  Re: [RFC PATCH] timer: Improve itimers scalability Peter Zijlstra <peterz@infradead.org> - 2015-08-05 11:40 +0200
    Re: [RFC PATCH] timer: Improve itimers scalability Jason Low <jason.low2@hp.com> - 2015-08-05 22:00 +0200
  Re: [RFC PATCH] timer: Improve itimers scalability Oleg Nesterov <oleg@redhat.com> - 2015-08-06 16:30 +0200
    Re: [RFC PATCH] timer: Improve itimers scalability Jason Low <jason.low2@hp.com> - 2015-08-06 20:30 +0200
      Re: [RFC PATCH] timer: Improve itimers scalability Oleg Nesterov <oleg@redhat.com> - 2015-08-07 14:10 +0200

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