From: Johannes Weiner <hannes@cmpxchg.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de, mingo@kernel.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
bristot@redhat.com, bsingharora@gmail.com, pbonzini@redhat.com,
maz@kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, riel@surriel.com
Subject: Re: [PATCH 1/6] delayacct: Use sched_clock()
Date: Thu, 6 May 2021 09:59:11 -0400 [thread overview]
Message-ID: <YJP2L1lUvUrur4pK@cmpxchg.org> (raw)
In-Reply-To: <20210505111525.001031466@infradead.org>
On Wed, May 05, 2021 at 12:59:41PM +0200, Peter Zijlstra wrote:
> @@ -42,10 +42,9 @@ void __delayacct_tsk_init(struct task_st
> * Finish delay accounting for a statistic using its timestamps (@start),
> * accumalator (@total) and @count
> */
> -static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total,
> - u32 *count)
> +static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count)
> {
> - s64 ns = ktime_get_ns() - *start;
> + s64 ns = local_clock() - *start;
I don't think this is safe. These time sections that have preemption
and migration enabled and so might span multiple CPUs. local_clock()
could end up behind *start, AFAICS.
next prev parent reply other threads:[~2021-05-06 13:59 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-05 10:59 [PATCH 0/6] sched,delayacct: Some cleanups Peter Zijlstra
2021-05-05 10:59 ` [PATCH 1/6] delayacct: Use sched_clock() Peter Zijlstra
2021-05-05 14:40 ` Rik van Riel
2021-05-06 13:59 ` Johannes Weiner [this message]
2021-05-06 14:17 ` Peter Zijlstra
2021-05-06 15:17 ` Johannes Weiner
2021-05-07 12:40 ` Balbir Singh
2021-05-12 10:43 ` Mel Gorman
2021-05-05 10:59 ` [PATCH 2/6] sched: Rename sched_info_{queued,dequeued} Peter Zijlstra
2021-05-05 14:39 ` Rik van Riel
2021-05-06 13:59 ` Johannes Weiner
2021-05-10 8:45 ` Balbir Singh
2021-05-12 10:49 ` Mel Gorman
2021-05-05 10:59 ` [PATCH 3/6] sched: Simplify sched_info_on() Peter Zijlstra
2021-05-06 14:03 ` Johannes Weiner
2021-05-12 11:10 ` Mel Gorman
2021-05-12 11:32 ` Peter Zijlstra
2021-05-12 12:51 ` Mel Gorman
2021-05-05 10:59 ` [PATCH 4/6] kvm: Select SCHED_INFO instead of TASK_DELAY_ACCT Peter Zijlstra
2021-05-05 11:37 ` Paolo Bonzini
2021-05-06 14:38 ` Marc Zyngier
2021-05-07 12:42 ` Balbir Singh
2021-05-12 11:11 ` Mel Gorman
2021-05-05 10:59 ` [PATCH 5/6] delayacct: Add static_branch in scheduler hooks Peter Zijlstra
2021-05-06 14:05 ` Johannes Weiner
2021-05-10 8:42 ` Balbir Singh
2021-05-12 11:13 ` Mel Gorman
2021-05-05 10:59 ` [PATCH 6/6] [RFC] delayacct: Default disabled Peter Zijlstra
2021-05-12 11:35 ` Mel Gorman
2021-05-05 22:29 ` [PATCH 0/6] sched,delayacct: Some cleanups Balbir Singh
2021-05-06 9:13 ` Peter Zijlstra
2021-05-07 12:38 ` Balbir Singh
2021-05-12 11:34 ` Mel Gorman
2021-05-12 11:38 ` Peter Zijlstra
2021-05-12 12:23 ` Paul Wise
2021-05-12 13:00 ` Mel Gorman
2021-05-13 1:29 ` Paul Wise
2021-06-25 0:50 ` Paul Wise
2021-05-07 9:05 ` Thomas Gleixner
2021-05-10 7:08 ` Ingo Molnar
2021-05-10 12:05 ` [PATCH 7/6] delayacct: Add sysctl to enable at runtime Peter Zijlstra
2021-05-10 12:06 ` Peter Zijlstra
2021-05-12 11:40 ` Mel Gorman
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