All of lore.kernel.org
 help / color / mirror / Atom feed
From: Ingo Molnar <mingo@elte.hu>
To: "Siddha, Suresh B" <suresh.b.siddha@intel.com>,
	discuss@LessWatts.org,
	Linux-pm mailing list <linux-pm@lists.linux-foundation.org>,
	Linux Kernel <linux-kernel@vger.kernel>
Subject: Re: Analysis of sched_mc_power_savings
Date: Wed, 9 Jan 2008 14:20:14 +0100	[thread overview]
Message-ID: <20080109132014.GF27196@elte.hu> (raw)
In-Reply-To: <20080109122847.GA28955@dirshya.in.ibm.com>


* Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> wrote:

> I will watch this during the experiments.  I have been using klog 
> application to dump relayfs data.  I did run powertop and top as well, 
> I will bind them to certain CPUs and isolate their impact.
> 
> I believe the margin of error would be less since all the measurement 
> tasks sleep for long duration.

ok, long duration ought to be enough.

i think a possible explanation of your observtions would be this: sleepy 
workloads are affected more by the wakeup logic, and most of the 
power-savings works via runtime balancing.

So perhaps try to add some SD_POWERSAVINGS_BALANCE logic to 
try_to_wake_up()? I think waking up on the same CPU where it went to 
sleep is the most power-efficient approach in general. (or always waking 
up where the wakee runs - this should be measured.) Right now 
try_to_wake_up() tries to spread out load opportunistically, which is 
throughput-maximizing but it's arguably not very power conscious.

	Ingo

WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@elte.hu>
To: "Siddha, Suresh B" <suresh.b.siddha@intel.com>,
	discuss@LessWatts.org,
	Linux-pm mailing list <linux-pm@lists.linux-foundation.org>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Dipankar Sarma <dipankar@in.ibm.com>,
	venkatesh.pallipadi@intel.com, tglx@linutronix.de,
	Arjan van de Ven <arjan@infradead.org>,
	Gautham R Shenoy <ego@in.ibm.com>,
	Chanda Sethia <chanda.sethia@in.ibm.com>
Subject: Re: Analysis of sched_mc_power_savings
Date: Wed, 9 Jan 2008 14:20:14 +0100	[thread overview]
Message-ID: <20080109132014.GF27196@elte.hu> (raw)
In-Reply-To: <20080109122847.GA28955@dirshya.in.ibm.com>


* Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> wrote:

> I will watch this during the experiments.  I have been using klog 
> application to dump relayfs data.  I did run powertop and top as well, 
> I will bind them to certain CPUs and isolate their impact.
> 
> I believe the margin of error would be less since all the measurement 
> tasks sleep for long duration.

ok, long duration ought to be enough.

i think a possible explanation of your observtions would be this: sleepy 
workloads are affected more by the wakeup logic, and most of the 
power-savings works via runtime balancing.

So perhaps try to add some SD_POWERSAVINGS_BALANCE logic to 
try_to_wake_up()? I think waking up on the same CPU where it went to 
sleep is the most power-efficient approach in general. (or always waking 
up where the wakee runs - this should be measured.) Right now 
try_to_wake_up() tries to spread out load opportunistically, which is 
throughput-maximizing but it's arguably not very power conscious.

	Ingo

  reply	other threads:[~2008-01-09 13:20 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-08 17:38 Analysis of sched_mc_power_savings Vaidyanathan Srinivasan
2008-01-08 21:24 ` Siddha, Suresh B
2008-01-09 11:13   ` Vaidyanathan Srinivasan
2008-01-09 11:35     ` Ingo Molnar
2008-01-09 12:28       ` Vaidyanathan Srinivasan
2008-01-09 12:28       ` Vaidyanathan Srinivasan
2008-01-09 13:20         ` Ingo Molnar [this message]
2008-01-09 13:20           ` Ingo Molnar
2008-01-09 11:35     ` Ingo Molnar
2008-01-09 11:13   ` Vaidyanathan Srinivasan
2008-01-08 21:24 ` Siddha, Suresh B
  -- strict thread matches above, loose matches on Subject: below --
2008-01-08 17:38 Vaidyanathan Srinivasan

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=20080109132014.GF27196@elte.hu \
    --to=mingo@elte.hu \
    --cc=discuss@LessWatts.org \
    --cc=linux-kernel@vger.kernel \
    --cc=linux-pm@lists.linux-foundation.org \
    --cc=suresh.b.siddha@intel.com \
    /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.