From: Valdis.Kletnieks@vt.edu
To: Nick Piggin <piggin@cyberone.com.au>
Cc: William Lee Irwin III <wli@holomorphy.com>,
Con Kolivas <kernel@kolivas.org>,
linux kernel mailing list <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH] O11int for interactivity
Date: Tue, 05 Aug 2003 00:54:10 -0400 [thread overview]
Message-ID: <200308050454.h754sBqM004950@turing-police.cc.vt.edu> (raw)
In-Reply-To: Your message of "Tue, 05 Aug 2003 13:38:34 +1000." <3F2F26BA.3060904@cyberone.com.au>
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On Tue, 05 Aug 2003 13:38:34 +1000, Nick Piggin said:
> Of course some minimum read _latency_ would be required: this
> could actually be done easily with strace come to think of it.
>
> Maybe some xmms mapped memory is being swapped out? But that
> would be more of a VM problem.
I was seeing some CPU-related pauses, but once Con's work got to O7 or so,
those disappeared. I'm *quite* convinced that the remaining glitches
are VM related, mostly because every glitch seems to be associated with
an increase in the 'pswpout' field in /proc/vmstat (yes, I tested with stuff like
"for (;;) do cat /proc/vmstat; sleep 1 done;".
The *odd* part is that the pgpgin, pgpgout, and pswpin numbers do *NOT*
seem to be correlated. High I/O loads from read/write don't seem to cause
a problem - untarring the Linux distro won't do it, running badblocks won't do it.
But if somebody has to swap out, all hell breaks loose...
Hmm.. looking at mm/page_io.c, it seems swap_writepage() calls get_swap_bio
with GFP_NOIO, while readdpage() uses GFP_KERNEL. I wonder if that GFP_NOIO is
causing ugliness - that's really __GFP_WAIT, and the comments in bio_alloc() are
pretty clear that it can block. And remember we're not getting into this code unless
we're already under memory pressure....
(And if somebody tells me how to instrument a -test2-mm4 kernel so I can tell if
I'm on crack or not, I'll happily do so....)
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next prev parent reply other threads:[~2003-08-05 4:54 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-30 0:38 [PATCH] O11int for interactivity Con Kolivas
2003-07-30 0:55 ` Con Kolivas
2003-07-30 1:08 ` Con Kolivas
2003-07-31 13:55 ` Szonyi Calin
2003-07-31 13:56 ` Con Kolivas
2003-07-31 15:21 ` Måns Rullgård
2003-07-31 21:38 ` William Lee Irwin III
2003-07-31 22:01 ` Robert Love
2003-07-30 8:29 ` Felipe Alfaro Solana
2003-07-30 8:43 ` Marc-Christian Petersen
2003-07-30 9:38 ` Con Kolivas
2003-07-30 9:45 ` Marc-Christian Petersen
2003-07-30 12:56 ` Felipe Alfaro Solana
2003-07-30 13:14 ` Wade
2003-07-31 21:43 ` William Lee Irwin III
2003-07-31 21:55 ` William Lee Irwin III
2003-08-01 10:44 ` Marc-Christian Petersen
2003-08-02 21:27 ` Marc-Christian Petersen
2003-08-02 22:55 ` William Lee Irwin III
2003-08-02 23:19 ` Marc-Christian Petersen
2003-08-04 19:06 ` Marc-Christian Petersen
2003-08-04 19:53 ` William Lee Irwin III
2003-08-05 0:56 ` Nick Piggin
2003-08-05 2:41 ` William Lee Irwin III
2003-08-05 3:07 ` Nick Piggin
2003-08-05 3:13 ` William Lee Irwin III
2003-08-05 3:23 ` Nick Piggin
2003-08-05 3:31 ` William Lee Irwin III
2003-08-05 3:38 ` Nick Piggin
2003-08-05 4:54 ` Valdis.Kletnieks [this message]
2003-08-05 5:02 ` William Lee Irwin III
2003-08-05 5:55 ` Andrew Morton
2003-08-05 7:11 ` Nick Piggin
2003-08-05 17:00 ` Martin Josefsson
2003-07-30 8:41 ` Felipe Alfaro Solana
2003-07-30 9:35 ` Con Kolivas
2003-07-30 15:33 ` Apurva Mehta
2003-07-31 16:58 ` Moritz Muehlenhoff
2003-07-30 10:31 Voluspa
2003-07-30 10:51 ` Con Kolivas
2003-07-30 11:20 ` Eugene Teo
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