From: Andrew Morton <akpm@linux-foundation.org>
To: "Alex Villacís Lasso" <avillaci@fiec.espol.edu.ec>
Cc: avillaci@ceibo.fiec.espol.edu.ec,
bugzilla-daemon@bugzilla.kernel.org,
bugme-daemon@bugzilla.kernel.org, linux-mm@kvack.org,
Mel Gorman <mel@csn.ul.ie>
Subject: Re: [Bugme-new] [Bug 31142] New: Large write to USB stick freezes unrelated tasks for a long time
Date: Thu, 17 Mar 2011 14:47:27 -0700 [thread overview]
Message-ID: <20110317144727.87a461f9.akpm@linux-foundation.org> (raw)
In-Reply-To: <4D827CC1.4090807@fiec.espol.edu.ec>
On Thu, 17 Mar 2011 16:27:29 -0500
Alex Villac____s Lasso <avillaci@fiec.espol.edu.ec> wrote:
> > So it appears that the system is full of dirty pages against a slow
> > device and your foreground processes have got stuck in direct reclaim
> > -> compaction -> migration. That's Mel ;)
> >
> > What happened to the plans to eliminate direct reclaim?
> >
> >
> Browsing around bugzilla, I believe that bug 12309 looks very similar to the issue I am experiencing, especially from comment #525 onwards. Am I correct in this?
ah, the epic 12309. https://bugzilla.kernel.org/show_bug.cgi?id=12309.
If you're ever wondering how much we suck, go read that one.
I think what we're seeing in 31142 is a large amount of dirty data
buffered against a slow device. Innocent processes enter page reclaim
and end up getting stuck trying to write to that heavily-queued and
slow device.
If so, that's probably what some of the 12309 participants are seeing.
But there are lots of other things in that report too.
Now, the problem you're seeing in 31142 isn't really supposed to
happen. In the direct-reclaim case the code will try to avoid
initiation of blocking I/O against a congested device, via the
bdi_write_congested() test in may_write_to_queue(). Although that code
now looks a bit busted for the order>PAGE_ALLOC_COSTLY_ORDER case,
whodidthat.
However in the case of the new(ish) compaction/migration code I don't
think we're performing that test. migrate_pages()->unmap_and_move()
will get stuck behind that large&slow IO queue if page reclaim decided
to pass it down sync==true, as it apparently has done.
IOW, Mel broke it ;)
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-03-17 21:48 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-31142-10286@https.bugzilla.kernel.org/>
2011-03-15 20:53 ` [Bugme-new] [Bug 31142] New: Large write to USB stick freezes unrelated tasks for a long time Andrew Morton
2011-03-15 22:53 ` Alex Villacís Lasso
2011-03-15 23:19 ` Andrew Morton
2011-03-16 15:25 ` Alex Villacís Lasso
2011-03-16 22:02 ` Andrew Morton
2011-03-17 21:27 ` Alex Villacís Lasso
2011-03-17 21:47 ` Andrew Morton [this message]
2011-03-17 22:11 ` Alex Villacís Lasso
2011-03-17 22:25 ` Andrew Morton
2011-03-18 11:13 ` Mel Gorman
2011-03-18 12:26 ` Andrea Arcangeli
2011-03-18 18:05 ` Alex Villacís Lasso
2011-03-19 13:46 ` Mel Gorman
2011-03-19 16:04 ` Alex Villacís Lasso
2011-03-19 23:51 ` Andrea Arcangeli
2011-03-21 9:41 ` Mel Gorman
2011-03-21 13:48 ` Andrea Arcangeli
2011-03-21 15:22 ` Alex Villacís Lasso
2011-03-21 15:36 ` Alex Villacís Lasso
2011-03-21 15:40 ` Andrea Arcangeli
2011-03-21 16:37 ` Mel Gorman
2011-03-21 17:05 ` Alex Villacís Lasso
2011-03-21 20:16 ` Andrea Arcangeli
2011-03-21 23:35 ` Alex Villacís Lasso
2011-03-22 11:20 ` Mel Gorman
2011-03-22 15:03 ` Andrea Arcangeli
2011-03-22 20:34 ` Alex Villacís Lasso
2011-03-22 21:40 ` Andrea Arcangeli
2011-03-23 0:37 ` Andrea Arcangeli
2011-03-23 16:51 ` Alex Villacís Lasso
2011-04-04 15:37 ` Alex Villacís Lasso
2011-04-08 19:09 ` Andrea Arcangeli
2011-04-08 20:06 ` Alex Villacís Lasso
2011-04-12 16:27 ` Alex Villacís Lasso
2011-04-14 17:25 ` Alex Villacís Lasso
2011-04-14 17:37 ` Andrea Arcangeli
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=20110317144727.87a461f9.akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=avillaci@ceibo.fiec.espol.edu.ec \
--cc=avillaci@fiec.espol.edu.ec \
--cc=bugme-daemon@bugzilla.kernel.org \
--cc=bugzilla-daemon@bugzilla.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mel@csn.ul.ie \
/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).