From: Dave Chinner <david@fromorbit.com>
To: Yannis Klonatos <klonatos@ics.forth.gr>
Cc: xfs@oss.sgi.com
Subject: Re: xfs_buf and buffercache/pagecache connection
Date: Tue, 1 Jun 2010 08:06:03 +1000 [thread overview]
Message-ID: <20100531220603.GF1395@dastard> (raw)
In-Reply-To: <4C03E46B.9040407@ics.forth.gr>
On Mon, May 31, 2010 at 07:31:39PM +0300, Yannis Klonatos wrote:
> Hello,
>
> I was looking to add a kernel hook to my system in order to
> monitor buffer-cache hit and misses. Initially I was
> planning to add my modifications to the __getblk(). However, i
> noticed that XFS does not directly use the buffer-cache
> for its pages but it seems to implement its own buffer.
> What I am now looking for is 1) the place where XFS checks
> whether a page exists in its buffer or not and 2)
> what are the possible interactions between xfs_buf and the Linux
> kernel buffer-cache.
> I would appreciate any information regarding the above issues.
There are already stats in place to tell you about this.
http://xfs.org/index.php/Runtime_Stats#buf_-_Buf_Statistics
They aren't documented there, but if you look at
fs/xfs/linux-2.6/xfs_buf.c an search for XFS_STATS_INC you'll find
what they all mean from the code. It isn't as simple as hit or miss
counters - there's different counters for different types of hits
and misses....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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prev parent reply other threads:[~2010-05-31 22:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-31 16:31 xfs_buf and buffercache/pagecache connection Yannis Klonatos
2010-05-31 18:04 ` Andi Kleen
2010-05-31 18:25 ` Yannis Klonatos
2010-05-31 22:06 ` Dave Chinner [this message]
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