From: Peter Zijlstra <peterz@infradead.org>
To: Jason Low <jason.low2@hp.com>
Cc: Ingo Molnar <mingo@kernel.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Oleg Nesterov <oleg@redhat.com>,
Mike Galbraith <umgwanakikbuti@gmail.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Scott J Norton <scott.norton@hp.com>,
Chegu Vinod <chegu_vinod@hp.com>,
Aswin Chandramouleeswaran <aswin@hp.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] sched, timer: Use atomics for thread_group_cputimer stats
Date: Fri, 23 Jan 2015 10:25:08 +0100 [thread overview]
Message-ID: <20150123092508.GJ2896@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <1421983913.4432.22.camel@j-VirtualBox>
On Thu, Jan 22, 2015 at 07:31:53PM -0800, Jason Low wrote:
> +static void update_gt_cputime(struct thread_group_cputimer *a, struct task_cputime *b)
> {
> + if (b->utime > atomic64_read(&a->utime))
> + atomic64_set(&a->utime, b->utime);
>
> + if (b->stime > atomic64_read(&a->stime))
> + atomic64_set(&a->stime, b->stime);
>
> + if (b->sum_exec_runtime > atomic64_read(&a->sum_exec_runtime))
> + atomic64_set(&a->sum_exec_runtime, b->sum_exec_runtime);
> }
See something like this is not safe against concurrent adds.
next prev parent reply other threads:[~2015-01-23 9:25 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-23 3:31 [RFC PATCH] sched, timer: Use atomics for thread_group_cputimer stats Jason Low
2015-01-23 8:57 ` Peter Zijlstra
2015-01-23 9:25 ` Peter Zijlstra [this message]
2015-01-23 19:23 ` Jason Low
2015-01-23 20:08 ` Peter Zijlstra
2015-01-23 23:39 ` Jason Low
2015-01-23 23:45 ` Jason Low
2015-01-26 17:12 ` Peter Zijlstra
2015-01-23 9:33 ` Peter Zijlstra
2015-01-23 18:07 ` Jason Low
2015-01-23 20:11 ` Peter Zijlstra
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