From: Mel Gorman <mel@csn.ul.ie>
To: Dimitri Sivanich <sivanich@sgi.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@gentwo.org>,
David Rientjes <rientjes@google.com>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: [PATCH] cache align vm_stat
Date: Thu, 27 Oct 2011 10:50:25 +0200 [thread overview]
Message-ID: <20111027085008.GA6563@csn.ul.ie> (raw)
On Mon, Oct 24, 2011 at 11:10:35AM -0500, Dimitri Sivanich wrote:
> Avoid false sharing of the vm_stat array.
>
> This was found to adversely affect tmpfs I/O performance.
>
I think this fix is overly simplistic. It is moving each counter into
its own cache line. While I accept that this will help the preformance
of the tmpfs-based workload, it will adversely affect workloads that
touch a lot of counters because of the increased cache footprint.
1. Is it possible to rearrange the vmstat array such that two hot
counters do not share a cache line?
2. Has Andrew's suggestion to alter the per-cpu threshold based on the
value of the global counter to reduce conflicts been tried?
(I'm at Linux Con at the moment so will be even slower to respond than
usual)
--
Mel Gorman
SUSE Labs
--
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 internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next reply other threads:[~2011-10-27 8:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-27 8:50 Mel Gorman [this message]
2011-10-27 12:51 ` [PATCH] cache align vm_stat Dimitri Sivanich
2011-10-27 14:29 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2011-10-24 16:10 Dimitri Sivanich
2011-10-27 2:31 ` Christoph Lameter
2011-10-28 22:54 ` Andrew Morton
2011-10-29 5:22 ` Christoph Lameter
2011-10-31 13:37 ` Dimitri Sivanich
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=20111027085008.GA6563@csn.ul.ie \
--to=mel@csn.ul.ie \
--cc=akpm@linux-foundation.org \
--cc=andi@firstfloor.org \
--cc=cl@gentwo.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=rientjes@google.com \
--cc=sivanich@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;
as well as URLs for NNTP newsgroup(s).