From: Oleg Nesterov <oleg@redhat.com>
To: Rik van Riel <riel@redhat.com>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
umgwanakikbuti@gmail.com, fweisbec@gmail.com,
akpm@linux-foundation.org, srao@redhat.com, lwoodman@redhat.com,
atheurer@redhat.com
Subject: Re: [PATCH v2 2/3] time,signal: protect resource use statistics with seqlock
Date: Sat, 16 Aug 2014 19:50:02 +0200 [thread overview]
Message-ID: <20140816175002.GA24994@redhat.com> (raw)
In-Reply-To: <20140816134010.26a9b572@annuminas.surriel.com>
On 08/16, Rik van Riel wrote:
>
> + do {
> + seq = nextseq;
> + read_seqbegin_or_lock(&sig->stats_lock, &seq);
> + times->utime = sig->utime;
> + times->stime = sig->stime;
> + times->sum_exec_runtime = sig->sum_sched_runtime;
> +
> + for_each_thread(tsk, t) {
> + task_cputime(t, &utime, &stime);
> + times->utime += utime;
> + times->stime += stime;
> + times->sum_exec_runtime += task_sched_runtime(t);
> + }
> + /* If lockless access failed, take the lock. */
> + nextseq = 1;
Yes, thanks, this answers my concerns.
Cough... can't resist, and I still think that we should take rcu_read_lock()
only around for_each_thread() and the patch expands the critical section for
no reason. But this is minor, I won't insist.
Oleg.
next prev parent reply other threads:[~2014-08-16 17:52 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-15 20:05 [PATCH 0/3] lockless sys_times and posix_cpu_clock_get riel
2014-08-15 20:05 ` [PATCH 1/3] exit: always reap resource stats in __exit_signal riel
2014-09-08 6:39 ` [tip:sched/core] exit: Always reap resource stats in __exit_signal() tip-bot for Rik van Riel
2014-08-15 20:05 ` [PATCH 2/3] time,signal: protect resource use statistics with seqlock riel
2014-08-16 14:11 ` Oleg Nesterov
2014-08-16 15:07 ` Rik van Riel
2014-08-16 17:40 ` [PATCH v2 " Rik van Riel
2014-08-16 17:50 ` Oleg Nesterov [this message]
2014-08-18 4:44 ` Mike Galbraith
2014-08-18 14:03 ` Rik van Riel
2014-08-19 14:26 ` Mike Galbraith
2014-09-08 6:39 ` [tip:sched/core] time, signal: Protect " tip-bot for Rik van Riel
2014-08-15 20:05 ` [PATCH 3/3] sched,time: atomically increment stime & utime riel
2014-08-16 14:55 ` Oleg Nesterov
2014-08-16 14:56 ` Oleg Nesterov
2014-09-08 6:40 ` [tip:sched/core] sched, time: Atomically " tip-bot for Rik van Riel
2014-08-19 21:21 ` [PATCH 0/3] lockless sys_times and posix_cpu_clock_get Andrew Theurer
2014-09-03 18:38 ` Rik van Riel
2014-09-04 7:48 ` Peter Zijlstra
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