From: Alex Shi <alex.shi@intel.com>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: "mingo@redhat.com" <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
Arjan van de Ven <arjan@linux.intel.com>,
Borislav Petkov <bp@alien8.de>, Paul Turner <pjt@google.com>,
Namhyung Kim <namhyung@kernel.org>,
Mike Galbraith <efault@gmx.de>,
Morten Rasmussen <morten.rasmussen@arm.com>,
gregkh@linuxfoundation.org,
Preeti U Murthy <preeti@linux.vnet.ibm.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Len Brown <len.brown@intel.com>,
rafael.j.wysocki@intel.com, jkosina@suse.cz,
clark.williams@gmail.com,
"tony.luck@intel.com" <tony.luck@intel.com>,
keescook@chromium.org, mgorman@suse.de, riel@redhat.com
Subject: Re: [patch v3 6/8] sched: consider runnable load average in move_tasks
Date: Tue, 09 Apr 2013 18:38:22 +0800 [thread overview]
Message-ID: <5163EF9E.4030005@intel.com> (raw)
In-Reply-To: <CAKfTPtDbiv2ACgem7k7YxcxgwGA4-JY1LcAg0B_XOVaOeE8aeQ@mail.gmail.com>
On 04/09/2013 04:58 PM, Vincent Guittot wrote:
>>> >> How do you ensure that runnable_avg_period and runnable_avg_sum are
>>> >> coherent ? an update of the statistic can occur in the middle of your
>>> >> sequence.
>> >
>> > Thanks for your question, Vincent!
>> > the runnable_avg_period and runnable_avg_sum, only updated in
>> > __update_entity_runnable_avg().
>> > Yes, I didn't see some locks to ensure the coherent of them. but they
>> > are updated closely, and it is not big deal even a little incorrect to
>> > their value. These data are collected periodically, don't need very very
>> > precise at every time.
>> > Am I right? :)
> The problem mainly appears during starting phase (the 1st 345ms) when
> runnable_avg_period has not reached the max value yet so you can have
> avg.runnable_avg_sum greater than avg.runnable_avg_period. In a worst
> case, runnable_avg_sum could be twice runnable_avg_period
Oh, That's a serious problem. Do you catch it in real word or in code?
Could you explain more for details?
--
Thanks
Alex
next prev parent reply other threads:[~2013-04-09 10:38 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-02 3:23 [patch v3 0/8] sched: use runnable avg in load balance Alex Shi
2013-04-02 3:23 ` [patch v3 1/8] Revert "sched: Introduce temporary FAIR_GROUP_SCHED dependency for load-tracking" Alex Shi
2013-04-02 3:23 ` [patch v3 2/8] sched: set initial value of runnable avg for new forked task Alex Shi
2013-04-02 3:23 ` [patch v3 3/8] sched: only count runnable avg on cfs_rq's nr_running Alex Shi
2013-04-03 3:19 ` Alex Shi
2013-04-02 3:23 ` [patch v3 4/8] sched: update cpu load after task_tick Alex Shi
2013-04-02 3:23 ` [patch v3 5/8] sched: compute runnable load avg in cpu_load and cpu_avg_load_per_task Alex Shi
2013-04-02 3:23 ` [patch v3 6/8] sched: consider runnable load average in move_tasks Alex Shi
2013-04-09 7:08 ` Vincent Guittot
2013-04-09 8:05 ` Alex Shi
2013-04-09 8:58 ` Vincent Guittot
2013-04-09 10:38 ` Alex Shi [this message]
2013-04-09 11:56 ` Vincent Guittot
2013-04-09 14:48 ` Alex Shi
2013-04-09 15:16 ` Vincent Guittot
2013-04-10 2:31 ` Alex Shi
2013-04-10 6:07 ` Michael Wang
2013-04-10 6:55 ` Vincent Guittot
2013-04-02 3:23 ` [patch v3 7/8] sched: consider runnable load average in effective_load Alex Shi
2013-04-02 3:23 ` [patch v3 8/8] sched: use instant load for burst wake up Alex Shi
2013-04-02 7:23 ` [patch v3 0/8] sched: use runnable avg in load balance Michael Wang
2013-04-02 8:34 ` Mike Galbraith
2013-04-02 9:13 ` Michael Wang
2013-04-02 8:35 ` Alex Shi
2013-04-02 9:45 ` Michael Wang
2013-04-03 2:46 ` Michael Wang
2013-04-03 2:56 ` Alex Shi
2013-04-03 3:23 ` Michael Wang
2013-04-03 4:28 ` Alex Shi
2013-04-03 5:38 ` Michael Wang
2013-04-03 5:53 ` Michael Wang
2013-04-03 6:01 ` Alex Shi
2013-04-03 6:22 ` Michael Wang
2013-04-03 6:53 ` Alex Shi
2013-04-03 7:18 ` Michael Wang
2013-04-03 7:28 ` Alex Shi
2013-04-03 8:46 ` Alex Shi
2013-04-03 9:37 ` Michael Wang
2013-04-03 11:17 ` Alex Shi
2013-04-07 3:09 ` Michael Wang
2013-04-07 7:30 ` Alex Shi
2013-04-07 8:56 ` Michael Wang
2013-04-09 5:08 ` Alex Shi
2013-04-10 13:12 ` Alex Shi
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