linux-kernel - Re: [RFC PATCH] v2 mm: balance_dirty_pages. reduce calls to global_page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20090906184214.GL18599@kernel.dk>
Date:	Sun, 6 Sep 2009 20:42:14 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	Richard Kennedy <richard@....demon.co.uk>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Wu Fengguang <fengguang.wu@...el.com>,
	"chris.mason" <chris.mason@...cle.com>,
	linux-mm <linux-mm@...ck.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [RFC PATCH] v2 mm: balance_dirty_pages.  reduce calls to
	global_page_state to reduce cache references

On Fri, Sep 04 2009, Richard Kennedy wrote:
> Reducing the number of times balance_dirty_pages calls global_page_state
> reduces the cache references and so improves write performance on a
> variety of workloads.
> 
> 'perf stats' of simple fio write tests shows the reduction in cache
> access.
> Where the test is fio 'write,mmap,600Mb,pre_read' on AMD AthlonX2 with
> 3Gb memory (dirty_threshold approx 600 Mb)
> running each test 10 times, dropping the fasted & slowest values then
> taking 
> the average & standard deviation
> 
> 		average (s.d.) in millions (10^6)
> 2.6.31-rc8	648.6 (14.6)
> +patch		620.1 (16.5)

This patch looks good to me, I have workloads too here where up to 10%
of the time is spent in balance_dirty_pages() because of this. I'll give
this patch a go on the box and test in question tomorrow, but it looks
promising.

-- 
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/