All of lore.kernel.org
 help / color / mirror / Atom feed
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

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=5163EF9E.4030005@intel.com \
    --to=alex.shi@intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=arjan@linux.intel.com \
    --cc=bp@alien8.de \
    --cc=clark.williams@gmail.com \
    --cc=efault@gmx.de \
    --cc=gregkh@linuxfoundation.org \
    --cc=jkosina@suse.cz \
    --cc=keescook@chromium.org \
    --cc=len.brown@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mgorman@suse.de \
    --cc=mingo@redhat.com \
    --cc=morten.rasmussen@arm.com \
    --cc=namhyung@kernel.org \
    --cc=peterz@infradead.org \
    --cc=pjt@google.com \
    --cc=preeti@linux.vnet.ibm.com \
    --cc=rafael.j.wysocki@intel.com \
    --cc=riel@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=tony.luck@intel.com \
    --cc=vincent.guittot@linaro.org \
    --cc=viresh.kumar@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.