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From: Michael Monnerie <michael.monnerie@is.it-management.at>
To: xfs@oss.sgi.com
Subject: Re: I/O hang, possibly XFS, possibly general
Date: Mon, 6 Jun 2011 09:29:01 +0200	[thread overview]
Message-ID: <201106060929.06814@zmi.at> (raw)
In-Reply-To: <19945.24042.711472.158523@tree.ty.sabi.co.UK>


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On Samstag, 4. Juni 2011 Peter Grandi wrote:
>   vm/dirty_ratio=2
>   vm/dirty_bytes=400000000
> 
>   vm/dirty_background_ratio=60
>   vm/dirty_background_bytes=0
> 
>   vm/dirty_expire_centisecs=200
>   vm/dirty_writeback_centisecs=400

Why dirty_background_ratio=60? This would mean you start to write dirty 
pages only after it reaches 60% of total system memory... Setting it to 
=1 would be the thing you want I guess.
Also, setting both dirty_background_(ratio|bytes) is not supported. The 
latter wins, according to sysctl/vm.txt

Similarly, dirty_ratio and dirty_bytes belong together and exclude each 
other. Maybe you specified both to fit older and newer kernels in one 
example?

dirty_expire_centisecs to 200 means a sync every 2s, which might be good 
in this specific setup mentioned here, but not for a generic server. 
That would defeat XFS's in-memory grouping of blocks before writeout, 
and in case of many parallel (slow|ftp) uploads could lead to much more 
data fragmentation, or no?


-- 
mit freundlichen Grüssen,
Michael Monnerie, Ing. BSc

it-management Internet Services: Protéger
http://proteger.at [gesprochen: Prot-e-schee]
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  reply	other threads:[~2011-06-06  7:29 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-02 14:42 I/O hang, possibly XFS, possibly general Paul Anderson
2011-06-02 16:17 ` Stan Hoeppner
2011-06-02 18:56 ` Peter Grandi
2011-06-02 21:24   ` Paul Anderson
2011-06-02 23:59     ` Phil Karn
2011-06-03  0:39       ` Dave Chinner
2011-06-03  2:11         ` Phil Karn
2011-06-03  2:54           ` Dave Chinner
2011-06-03 22:28             ` Phil Karn
2011-06-04  3:12               ` Dave Chinner
2011-06-03 22:19     ` Peter Grandi
2011-06-06  7:29       ` Michael Monnerie [this message]
2011-06-07 14:09         ` Peter Grandi
2011-06-08  5:18           ` Dave Chinner
2011-06-08  8:32           ` Michael Monnerie
2011-06-03  0:06   ` Phil Karn
2011-06-03  0:42 ` Christoph Hellwig
2011-06-03  1:39   ` Dave Chinner
2011-06-03 15:59     ` Paul Anderson
2011-06-04  3:15       ` Dave Chinner
2011-06-04  8:14       ` Stan Hoeppner
2011-06-04 10:32         ` Dave Chinner
2011-06-04 12:11           ` Stan Hoeppner
2011-06-04 23:10             ` Dave Chinner
2011-06-05  1:31               ` Stan Hoeppner

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