From: Peter Zijlstra <peterz@infradead.org>
To: Mike Galbraith <efault@gmx.de>
Cc: Luca Zini <luca.zini@gmail.com>,
aagaande@gmail.com, rdelcueto@hotmail.com, mingo@elte.hu,
linux-kernel <linux-kernel@vger.kernel.org>,
Alex Chiang <achiang@hp.com>
Subject: Re: scheduler vs hardware? (was Re: another i7 (linux) bug?)
Date: Fri, 22 Jan 2010 09:51:12 +0100 [thread overview]
Message-ID: <1264150272.4283.1361.camel@laptop> (raw)
In-Reply-To: <1264144758.8074.22.camel@marge.simson.net>
On Fri, 2010-01-22 at 08:19 +0100, Mike Galbraith wrote:
> > if I run a cpu intensive process with the lowest priority (19
> > from man nice) I obtain much better performance that with the
> > highest priority available (-20 from man nice).
> >
> > For example the same file is processed by lame in 8.7 seconds
> > at the lowest priority, and in 12 seconds at the highest
> > priority. Before posting a bug I wold like to understand if
> > this is a problem related to the i7 mobile (my processor is a
> > i7 Q720).
> >
> > As far as I tested on the same laptop series (dell studio 15),
> > with the same kernel this problem does not exists.
>
> So you only see this on the i7. That's odd. Can you try 33-rc5?
>
> Posting a reliable reproducer would be nice. It'd also be nice to see
> what all is running when you see this, and where.
Using a sample from: http://lame.sourceforge.net/quality.php
My laptop does:
# time nice -n 19 lame -b 256 -V0 -h youcantdothat.wav - > /dev/null
LAME 3.98.2 64bits (http://www.mp3dev.org/)
Using polyphase lowpass filter, transition band: 19383 Hz - 19916 Hz
Encoding youcantdothat.wav to <stdout>
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III VBR(q=0)
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
1147/1147 (100%)| 0:03/ 0:03| 0:03/ 0:03| 9.3341x| 0:00
32 [ 1] *
256 [1009] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
320 [ 137] %%%%%%%%%
----------------------------------------------------------------------------
kbps LR MS % long switch short %
263.4 99.1 0.9 90.5 5.5 4.0
real 0m3.273s
user 0m3.217s
sys 0m0.022s
# time nice -n 0 lame -b 256 -V0 -h youcantdothat.wav - > /dev/null
LAME 3.98.2 64bits (http://www.mp3dev.org/)
Using polyphase lowpass filter, transition band: 19383 Hz - 19916 Hz
Encoding youcantdothat.wav to <stdout>
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III VBR(q=0)
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
1147/1147 (100%)| 0:01/ 0:01| 0:01/ 0:01| 27.239x| 0:00
32 [ 1] *
256 [1009] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
320 [ 137] %%%%%%%%%
----------------------------------------------------------------------------
kbps LR MS % long switch short %
263.4 99.1 0.9 90.5 5.5 4.0
real 0m1.121s
user 0m1.102s
sys 0m0.013s
# time nice -n -20 lame -b 256 -V0 -h youcantdothat.wav - > /dev/null
LAME 3.98.2 64bits (http://www.mp3dev.org/)
Using polyphase lowpass filter, transition band: 19383 Hz - 19916 Hz
Encoding youcantdothat.wav to <stdout>
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III VBR(q=0)
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
1147/1147 (100%)| 0:01/ 0:01| 0:01/ 0:01| 27.239x| 0:00
32 [ 1] *
256 [1009] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
320 [ 137] %%%%%%%%%
----------------------------------------------------------------------------
kbps LR MS % long switch short %
263.4 99.1 0.9 90.5 5.5 4.0
real 0m1.112s
user 0m1.093s
sys 0m0.018s
On a Nehalem class server machine it does:
# time nice -n 19 lame -b 256 -V0 -h youcantdothat.wav - > /dev/null
LAME 3.98.2 64bits (http://www.mp3dev.org/)
Using polyphase lowpass filter, transition band: 19383 Hz - 19916 Hz
Encoding youcantdothat.wav to <stdout>
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III VBR(q=0)
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
1147/1147 (100%)| 0:00/ 0:00| 0:00/ 0:00| 32.926x| 0:00
32 [ 1] *
256 [1009] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
320 [ 137] %%%%%%%%%
----------------------------------------------------------------------------
kbps LR MS % long switch short %
263.4 99.1 0.9 90.5 5.5 4.0
real 0m0.932s
user 0m0.917s
sys 0m0.005s
# time nice -n 0 lame -b 256 -V0 -h youcantdothat.wav - > /dev/null
LAME 3.98.2 64bits (http://www.mp3dev.org/)
Using polyphase lowpass filter, transition band: 19383 Hz - 19916 Hz
Encoding youcantdothat.wav to <stdout>
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III VBR(q=0)
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
1147/1147 (100%)| 0:00/ 0:00| 0:00/ 0:00| 32.568x| 0:00
32 [ 1] *
256 [1009] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
320 [ 137] %%%%%%%%%
----------------------------------------------------------------------------
kbps LR MS % long switch short %
263.4 99.1 0.9 90.5 5.5 4.0
real 0m0.927s
user 0m0.922s
sys 0m0.003s
# time nice -n -20 lame -b 256 -V0 -h youcantdothat.wav - > /dev/null
LAME 3.98.2 64bits (http://www.mp3dev.org/)
Using polyphase lowpass filter, transition band: 19383 Hz - 19916 Hz
Encoding youcantdothat.wav to <stdout>
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III VBR(q=0)
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
1147/1147 (100%)| 0:00/ 0:00| 0:00/ 0:00| 32.926x| 0:00
32 [ 1] *
256 [1009] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
320 [ 137] %%%%%%%%%
----------------------------------------------------------------------------
kbps LR MS % long switch short %
263.4 99.1 0.9 90.5 5.5 4.0
real 0m0.919s
user 0m0.914s
sys 0m0.005s
next prev parent reply other threads:[~2010-01-22 8:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <201001211258.23499.luca.zini@gmail.com>
2010-01-21 21:54 ` scheduler vs hardware? (was Re: another i7 (linux) bug?) Alex Chiang
2010-01-22 7:19 ` Mike Galbraith
2010-01-22 8:51 ` Peter Zijlstra [this message]
2010-01-22 9:10 ` Mike Galbraith
2010-01-22 9:25 ` Mike Galbraith
2010-01-22 9:34 ` Peter Zijlstra
2010-01-22 11:22 ` Luca Zini
2010-01-22 15:58 ` Chris Friesen
2010-01-23 9:43 ` Ingo Molnar
2010-01-22 20:15 ` Luca Zini
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=1264150272.4283.1361.camel@laptop \
--to=peterz@infradead.org \
--cc=aagaande@gmail.com \
--cc=achiang@hp.com \
--cc=efault@gmx.de \
--cc=linux-kernel@vger.kernel.org \
--cc=luca.zini@gmail.com \
--cc=mingo@elte.hu \
--cc=rdelcueto@hotmail.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox