From: Christoph Lameter <cl@linux.com>
To: Arjan van de Ven <arjan@linux.intel.com>
Cc: Alex Shi <alex.shi@intel.com>,
Matthew Garrett <mjg59@srcf.ucam.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Suresh Siddha <suresh.b.siddha@intel.com>,
vincent.guittot@linaro.org, svaidy@linux.vnet.ibm.com,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [discussion]sched: a rough proposal to enable power saving in scheduler
Date: Mon, 20 Aug 2012 15:47:54 +0000 [thread overview]
Message-ID: <0000013944b80714-c594cc1e-de63-4901-9aa7-0b5a3d8629e5-000000@email.amazonses.com> (raw)
In-Reply-To: <502CFC41.1030501@linux.intel.com>
One issue that is often forgotten is that there are users who want lowest
latency and not highest performance. Our systems sit idle for most of the
time but when a specific event occurs (typically a packet is received)
they must react in the fastest way possible.
On every new generation of hardware and software we keep on running into
various mechanisms that automatically power down when idle for a long time
(to save power...). And its pretty hard to figure these things out given
the complexity of modern hardware. F.e. for the Sandybridges we found that
the memory channel powers down after 2 milliseconds idle time and that was
unaffected by any of the bios config options. Similar mechanisms exist in
the kernel but those are easier discover since there is source.
So please make sure that there are obvious and easy ways to switch this
stuff off or provide "low latency" know that keeps the system from
assuming that idle time means that full performance is not needed.
next prev parent reply other threads:[~2012-08-20 15:48 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-13 12:21 [discussion]sched: a rough proposal to enable power saving in scheduler Alex Shi
2012-08-14 7:35 ` Alex Shi
2012-08-15 8:23 ` Peter Zijlstra
2012-08-15 11:05 ` Peter Zijlstra
2012-08-15 13:15 ` Borislav Petkov
2012-08-15 14:43 ` Peter Zijlstra
2012-08-16 3:22 ` Alex Shi
2012-08-16 3:09 ` Alex Shi
2012-08-15 13:45 ` Arjan van de Ven
2012-08-15 14:39 ` Peter Zijlstra
2012-08-15 14:43 ` Arjan van de Ven
2012-08-15 15:04 ` Peter Zijlstra
2012-08-15 17:59 ` Arjan van de Ven
2012-08-20 8:06 ` Ingo Molnar
2012-08-20 8:26 ` Peter Zijlstra
2012-08-20 13:26 ` Arjan van de Ven
2012-08-20 18:16 ` Matthew Garrett
2012-08-21 9:42 ` Ingo Molnar
2012-08-21 11:39 ` Matthew Garrett
2012-08-21 15:19 ` Ingo Molnar
2012-08-21 15:21 ` Arjan van de Ven
2012-08-21 15:28 ` Matthew Garrett
2012-08-21 15:59 ` Ingo Molnar
2012-08-21 16:13 ` Matthew Garrett
2012-08-21 18:23 ` Ingo Molnar
2012-08-21 18:34 ` Matthew Garrett
2012-08-22 9:10 ` Ingo Molnar
2012-08-22 11:35 ` Matthew Garrett
2012-08-23 8:19 ` Alex Shi
2012-08-21 18:52 ` Alan Cox
2012-08-22 9:03 ` Ingo Molnar
2012-08-22 11:00 ` Alan Cox
2012-08-22 11:33 ` Ingo Molnar
2012-08-22 12:58 ` Alan Cox
2012-08-21 16:02 ` Alan Cox
2012-08-22 5:41 ` Mike Galbraith
2012-08-22 13:02 ` Arjan van de Ven
2012-08-22 13:09 ` Mike Galbraith
2012-08-22 13:21 ` Matthew Garrett
2012-08-22 13:23 ` Arjan van de Ven
2012-08-16 1:14 ` Rik van Riel
2012-08-16 1:17 ` Arjan van de Ven
2012-08-16 1:21 ` Arjan van de Ven
2012-08-15 14:19 ` Arjan van de Ven
2012-08-15 14:44 ` Peter Zijlstra
2012-08-15 14:47 ` Thomas Gleixner
2012-08-15 16:23 ` Matthew Garrett
2012-08-15 16:34 ` Matthew Garrett
2012-08-15 18:02 ` Arjan van de Ven
2012-08-17 8:59 ` Paul Turner
2012-08-16 3:07 ` Alex Shi
2012-08-16 6:53 ` preeti
2012-08-16 9:58 ` Alex Shi
2012-08-16 12:45 ` Shilimkar, Santosh
2012-08-16 14:01 ` Arjan van de Ven
2012-08-16 18:45 ` Rik van Riel
2012-08-16 19:20 ` Arjan van de Ven
2012-08-17 1:29 ` Alex Shi
2012-08-17 18:41 ` Matthew Garrett
2012-08-17 18:44 ` Arjan van de Ven
2012-08-17 18:47 ` Matthew Garrett
2012-08-17 19:45 ` Chris Friesen
2012-08-17 19:50 ` Matthew Garrett
2012-08-17 20:16 ` Chris Friesen
2012-08-18 14:33 ` Luming Yu
2012-08-18 14:52 ` Arjan van de Ven
2012-08-16 14:31 ` Morten Rasmussen
2012-08-19 10:12 ` Juri Lelli
2012-08-17 8:43 ` Paul Turner
2012-08-20 15:55 ` Vincent Guittot
2012-08-20 15:36 ` Vincent Guittot
2012-08-21 0:58 ` Alex Shi
2012-08-21 11:05 ` Vincent Guittot
2012-08-15 14:24 ` Rakib Mullick
2012-08-15 14:55 ` Peter Zijlstra
2012-08-15 22:58 ` Rakib Mullick
2012-08-16 5:26 ` Alex Shi
2012-08-16 4:57 ` Alex Shi
2012-08-16 8:05 ` Rakib Mullick
2012-08-15 16:19 ` Matthew Garrett
2012-08-16 5:03 ` Alex Shi
2012-08-16 5:31 ` Matthew Garrett
2012-08-16 5:39 ` Alex Shi
2012-08-16 5:45 ` Matthew Garrett
2012-08-16 13:57 ` Arjan van de Ven
2012-08-20 15:47 ` Christoph Lameter [this message]
2012-08-20 15:52 ` Matthew Garrett
2012-08-20 19:22 ` Christoph Lameter
2012-08-20 15:47 ` Vincent Guittot
2012-08-21 1:05 ` 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=0000013944b80714-c594cc1e-de63-4901-9aa7-0b5a3d8629e5-000000@email.amazonses.com \
--to=cl@linux.com \
--cc=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=alex.shi@intel.com \
--cc=arjan@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=mjg59@srcf.ucam.org \
--cc=suresh.b.siddha@intel.com \
--cc=svaidy@linux.vnet.ibm.com \
--cc=torvalds@linux-foundation.org \
--cc=vincent.guittot@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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).