From: Alex Elder <aelder@sgi.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 2/2] xfs: improve buffer cache hash scalability
Date: Fri, 27 Aug 2010 13:11:53 -0500 [thread overview]
Message-ID: <1282932713.2450.75.camel@doink> (raw)
In-Reply-To: <1282522546-7892-3-git-send-email-david@fromorbit.com>
On Mon, 2010-08-23 at 10:15 +1000, Dave Chinner wrote:
> When doing large parallel file creates on a 16p machines, large amounts of
> time is being spent in _xfs_buf_find(). A system wide profile with perf top
> shows this:
>
> 1134740.00 19.3% _xfs_buf_find
> 733142.00 12.5% __ticket_spin_lock
>
> The problem is that the hash contains 45,000 buffers, and the hash table width
> is only 256 buffers. That means we've got around 200 buffers per chain, and
> searching it is quite expensive. The hash table size needs to increase.
My only comment on this is that 4096 buckets is
good now but someday that may not be right either.
Is there any better way (based on size of underlying
block_device and maybe taking into account other things
like page size or CPU count) to decide this hash size?
Either way it looks good.
Reviewed-by: Alex Elder <aelder@sgi.com>
. . .
_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs
prev parent reply other threads:[~2010-08-27 18:11 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-23 0:15 [PATCH 0/2] xfs: Fix issues found doing large inode count testing Dave Chinner
2010-08-23 0:15 ` [PATCH 1/2] xfs: don't do memory allocation under the CIL context lock Dave Chinner
2010-08-23 10:32 ` Christoph Hellwig
2010-08-23 0:15 ` [PATCH 2/2] xfs: improve buffer cache hash scalability Dave Chinner
2010-08-23 10:36 ` Christoph Hellwig
2010-08-27 18:11 ` Alex Elder [this message]
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=1282932713.2450.75.camel@doink \
--to=aelder@sgi.com \
--cc=david@fromorbit.com \
--cc=xfs@oss.sgi.com \
/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