linux-kernel - Re: [PATCH] sched/cputime: Mitigate performance regression in times()/clock

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Message-ID: <20160803103442.GC7141@twins.programming.kicks-ass.net>
Date:	Wed, 3 Aug 2016 12:34:42 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Giovanni Gherdovich <ggherdovich@...e.cz>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Mike Galbraith <mgalbraith@...e.de>,
	Stanislaw Gruszka <sgruszka@...hat.com>,
	linux-kernel@...r.kernel.org, Mel Gorman <mgorman@...e.com>,
	mgorman@...hsingularity.net
Subject: Re: [PATCH] sched/cputime: Mitigate performance regression in
 times()/clock_gettime()

On Wed, Aug 03, 2016 at 12:02:54PM +0200, Peter Zijlstra wrote:
> /*
>  * XXX comment on why this is needed goes here...
>  */
> static inline void prefetch_curr_exec_start(struct task_struct *p)
> {
> #ifdef CONFIG_FAIR_GROUP_SCHED
> 	struct sched_entity *curr = (&p->se)->cfs_rq->curr;
#else
	struct sched_entity *curr = task_rq(p)->cfs_rq->curr;
#endif

Would be the 'right' thing for !cgroup stuffs

> 
> 	prefetch(curr);
> 	prefetch(&curr->exec_start);
> }