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From: Brian Candler <brian@soundmouse.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com
Subject: Re: Performance problem - reads slower than writes
Date: Tue, 31 Jan 2012 21:52:10 +0000	[thread overview]
Message-ID: <20120131215210.GB47420@soundmouse.com> (raw)
In-Reply-To: <20120131145205.GA6607@infradead.org>

On Tue, Jan 31, 2012 at 09:52:05AM -0500, Christoph Hellwig wrote:
> You don't just read a single file at a time but multiple ones, don't
> you?

It's sequential at the moment, although I'll do further tests with the -c
(concurrency) option to bonnie++

> Try playing with the following tweaks to get larger I/O to the disk:
> 
>  a) make sure you use the noop or deadline elevators
>  b) increase /sys/block/sdX/queue/max_sectors_kb from its low default
>  c) dramatically increase /sys/devices/virtual/bdi/<major>:<minor>/read_ahead_kb

Thank you very much: I will do further tests with these.

Is the read_ahead_kb knob aware of file boundaries? That is, is there any
risk that if I set it too large it would read useless blocks past the end of
the file?

Regards,

Brian.

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  reply	other threads:[~2012-01-31 21:52 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-30 22:00 Performance problem - reads slower than writes Brian Candler
2012-01-31  2:05 ` Dave Chinner
2012-01-31 10:31   ` Brian Candler
2012-01-31 14:16     ` Brian Candler
2012-01-31 20:25       ` Dave Chinner
2012-02-01  7:29         ` Stan Hoeppner
2012-02-03 18:47         ` Brian Candler
2012-02-03 19:03           ` Christoph Hellwig
2012-02-03 21:01             ` Brian Candler
2012-02-03 21:17               ` Brian Candler
2012-02-05 22:50                 ` Dave Chinner
2012-02-05 22:43               ` Dave Chinner
2012-01-31 14:52     ` Christoph Hellwig
2012-01-31 21:52       ` Brian Candler [this message]
2012-02-01  0:50         ` Raghavendra D Prabhu
2012-02-01  3:59         ` Dave Chinner
2012-02-03 11:54       ` Brian Candler
2012-02-03 19:42         ` Stan Hoeppner
2012-02-03 22:10           ` Brian Candler
2012-02-04  9:59             ` Stan Hoeppner
2012-02-04 11:24               ` Brian Candler
2012-02-04 12:49                 ` Stan Hoeppner
2012-02-04 20:04                   ` Brian Candler
2012-02-04 20:44                     ` Joe Landman
2012-02-06 10:40                       ` Brian Candler
2012-02-07 17:30                       ` Brian Candler
2012-02-05  5:16                     ` Stan Hoeppner
2012-02-05  9:05                       ` Brian Candler
2012-01-31 20:06     ` Dave Chinner
2012-01-31 21:35       ` Brian Candler

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