From: Rik van Riel <riel@redhat.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Theodore Ts'o" <tytso@mit.edu>,
Chris Mason <chris.mason@oracle.com>,
Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.cz>,
Jens Axboe <axboe@kernel.dk>, Mel Gorman <mel@csn.ul.ie>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Christoph Hellwig <hch@lst.de>, linux-mm <linux-mm@kvack.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] writeback: enabling-gate for light dirtied bdi
Date: Sun, 05 Dec 2010 09:04:17 -0500 [thread overview]
Message-ID: <4CFB9BE1.3030902@redhat.com> (raw)
In-Reply-To: <20101205064430.GA15027@localhost>
On 12/05/2010 01:44 AM, Wu Fengguang wrote:
> I noticed that my NFSROOT test system goes slow responding when there
> is heavy dd to a local disk. Traces show that the NFSROOT's bdi_limit
> is near 0 and many tasks in the system are repeatedly stuck in
> balance_dirty_pages().
>
> There are two related problems:
>
> - light dirtiers at one device (more often than not the rootfs) get
> heavily impacted by heavy dirtiers on another independent device
>
> - the light dirtied device does heavy throttling because bdi_limit=0,
> and the heavy throttling may in turn withhold its bdi_limit in 0 as
> it cannot dirty fast enough to grow up the bdi's proportional weight.
>
> Fix it by introducing some "low pass" gate, which is a small (<=8MB)
> value reserved by others and can be safely "stole" from the current
> global dirty margin. It does not need to be big to help the bdi gain
> its initial weight.
Makes a lot of sense to me.
Acked-by: Rik van Riel <riel@redhat.com>
--
All rights reversed
WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Theodore Ts'o" <tytso@mit.edu>,
Chris Mason <chris.mason@oracle.com>,
Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.cz>,
Jens Axboe <axboe@kernel.dk>, Mel Gorman <mel@csn.ul.ie>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Christoph Hellwig <hch@lst.de>, linux-mm <linux-mm@kvack.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] writeback: enabling-gate for light dirtied bdi
Date: Sun, 05 Dec 2010 09:04:17 -0500 [thread overview]
Message-ID: <4CFB9BE1.3030902@redhat.com> (raw)
In-Reply-To: <20101205064430.GA15027@localhost>
On 12/05/2010 01:44 AM, Wu Fengguang wrote:
> I noticed that my NFSROOT test system goes slow responding when there
> is heavy dd to a local disk. Traces show that the NFSROOT's bdi_limit
> is near 0 and many tasks in the system are repeatedly stuck in
> balance_dirty_pages().
>
> There are two related problems:
>
> - light dirtiers at one device (more often than not the rootfs) get
> heavily impacted by heavy dirtiers on another independent device
>
> - the light dirtied device does heavy throttling because bdi_limit=0,
> and the heavy throttling may in turn withhold its bdi_limit in 0 as
> it cannot dirty fast enough to grow up the bdi's proportional weight.
>
> Fix it by introducing some "low pass" gate, which is a small (<=8MB)
> value reserved by others and can be safely "stole" from the current
> global dirty margin. It does not need to be big to help the bdi gain
> its initial weight.
Makes a lot of sense to me.
Acked-by: Rik van Riel <riel@redhat.com>
--
All rights reversed
--
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 policy in Canada: sign http://dissolvethecrtc.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2010-12-05 14:05 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-05 6:44 [PATCH] writeback: enabling-gate for light dirtied bdi Wu Fengguang
2010-12-05 6:44 ` Wu Fengguang
2010-12-05 14:04 ` Rik van Riel [this message]
2010-12-05 14:04 ` Rik van Riel
2010-12-07 13:11 ` [PATCH] writeback: safety margin for bdi stat errors Wu Fengguang
2010-12-07 13:11 ` Wu Fengguang
[not found] ` <20101207143351.GA23377@localhost>
2010-12-07 15:21 ` ext4 memory leak? Wu Fengguang
2010-12-07 16:38 ` Ted Ts'o
2010-12-07 16:38 ` Ted Ts'o
2010-12-08 2:40 ` Wu Fengguang
2010-12-08 2:40 ` Wu Fengguang
2010-12-08 3:07 ` Theodore Tso
2010-12-08 3:07 ` Theodore Tso
2010-12-08 6:10 ` Wu Fengguang
2010-12-08 6:10 ` Wu Fengguang
2010-12-07 17:34 ` [PATCH] writeback: safety margin for bdi stat errors Rik van Riel
2010-12-07 17:34 ` Rik van Riel
2010-12-08 0:51 ` [PATCH] writeback: enabling-gate for light dirtied bdi Andrew Morton
2010-12-08 0:51 ` Andrew Morton
2010-12-08 4:04 ` Wu Fengguang
2010-12-08 4:04 ` Wu Fengguang
2010-12-08 4:30 ` [PATCH v2] " Wu Fengguang
2010-12-08 4:30 ` Wu Fengguang
2010-12-08 4:37 ` [PATCH v2] writeback: safety margin for bdi stat error Wu Fengguang
2010-12-08 4:37 ` Wu Fengguang
2010-12-08 15:31 ` [PATCH v2] writeback: enabling-gate for light dirtied bdi Wu Fengguang
2010-12-08 15:31 ` Wu Fengguang
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=4CFB9BE1.3030902@redhat.com \
--to=riel@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=axboe@kernel.dk \
--cc=chris.mason@oracle.com \
--cc=david@fromorbit.com \
--cc=fengguang.wu@intel.com \
--cc=hch@lst.de \
--cc=jack@suse.cz \
--cc=kosaki.motohiro@jp.fujitsu.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mel@csn.ul.ie \
--cc=peterz@infradead.org \
--cc=tytso@mit.edu \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.