From: Clemens Ladisch <cladisch@googlemail.com>
To: Arthur Marsh <arthur.marsh@internode.on.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
alsa-user@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: Re: [Alsa-user] new source of MIDI playback slow-down identified - 5a03b051ed87e72b959f32a86054e1142ac4cf55 thp: use compaction in kswapd for GFP_ATOMIC order > 0
Date: Tue, 22 Feb 2011 08:37:23 +0100 [thread overview]
Message-ID: <4D6367B3.9050306@googlemail.com> (raw)
In-Reply-To: <g0ia38-jj6.ln1@ppp121-45-136-118.lns11.adl6.internode.on.net>
Arthur Marsh wrote:
> I'm experiencing MIDI playback slow-downs when I'm observing kswapd0
> active (a few percent of cpu in top output) in recent kernels.
>
> I git-bisected the problem down to:
>
> commit 5a03b051ed87e72b959f32a86054e1142ac4cf55
> Author: Andrea Arcangeli <aarcange@redhat.com>
> Date: Thu Jan 13 15:47:11 2011 -0800
>
> thp: use compaction in kswapd for GFP_ATOMIC order > 0
>
> This takes advantage of memory compaction to properly generate pages of
> order > 0 if regular page reclaim fails and priority level becomes more
> severe and we don't reach the proper watermarks.
>
> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
>
> I ran git-bisect over the weekend, building and installing ALSA 1.0.24
> with each kernel. After identifying the above commit, I rebuilt the 2.6
> head with that commit reverted and verified that the problem was no
> longer present.
Apparently, huge page compaction disables interrupts for much too long.
> MIDI playback was via aplaymidi -p 17:0 to a Soundblaster Audigy 2 ZS
> (SB0350) wavetable.
The ALSA sequencer uses either the system timer or an HR timer at 1 kHz
to deliver MIDI commands (notes); the wavetable driver requires its own
interrupts in regular 5.3 ms intervals.
Regards,
Clemens
next parent reply other threads:[~2011-02-22 7:43 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <g0ia38-jj6.ln1@ppp121-45-136-118.lns11.adl6.internode.on.net>
2011-02-22 7:37 ` Clemens Ladisch [this message]
2011-02-22 7:46 ` [Alsa-user] new source of MIDI playback slow-down identified - 5a03b051ed87e72b959f32a86054e1142ac4cf55 thp: use compaction in kswapd for GFP_ATOMIC order > 0 Arthur Marsh
2011-02-22 13:40 ` Andrea Arcangeli
2011-02-22 16:15 ` Andrea Arcangeli
2011-02-22 16:59 ` Mel Gorman
2011-02-22 17:08 ` Andrea Arcangeli
2011-02-22 17:37 ` Mel Gorman
2011-02-22 17:47 ` Arthur Marsh
2011-02-22 19:43 ` Andrea Arcangeli
2011-02-23 9:15 ` Mel Gorman
2011-02-23 11:41 ` Arthur Marsh
2011-02-23 13:50 ` Clemens Ladisch
2011-02-23 17:01 ` Mel Gorman
2011-02-23 17:40 ` Andrea Arcangeli
2011-02-23 16:24 ` Andrea Arcangeli
2011-02-23 16:36 ` Andrea Arcangeli
2011-02-23 16:40 ` Andrea Arcangeli
2011-02-23 16:47 ` Andrea Arcangeli
2011-02-23 16:55 ` Andrea Arcangeli
2011-02-23 20:07 ` Arthur Marsh
2011-02-23 21:25 ` Andrea Arcangeli
2011-02-23 21:55 ` Arthur Marsh
2011-02-23 23:59 ` Andrea Arcangeli
2011-02-24 1:40 ` Arthur Marsh
2011-02-24 1:54 ` Andrea Arcangeli
2011-02-26 6:43 ` Andrea Arcangeli
2011-02-27 8:48 ` Arthur Marsh
2011-02-23 17:10 ` Mel Gorman
2011-02-23 17:27 ` Andrea Arcangeli
2011-02-23 17:44 ` Mel Gorman
2011-02-23 18:14 ` Andrea Arcangeli
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