From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx203.postini.com [74.125.245.203]) by kanga.kvack.org (Postfix) with SMTP id 70E096B0081 for ; Tue, 15 May 2012 00:58:40 -0400 (EDT) Message-ID: <4FB1E2A0.9050900@kernel.org> Date: Tue, 15 May 2012 13:59:12 +0900 From: Minchan Kim MIME-Version: 1.0 Subject: Re: [PATCH 0/2] swap: improve swap I/O rate References: <1336996709-8304-1-git-send-email-ehrhardt@linux.vnet.ibm.com> In-Reply-To: <1336996709-8304-1-git-send-email-ehrhardt@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: ehrhardt@linux.vnet.ibm.com Cc: linux-mm@kvack.org, axboe@kernel.dk, Andrew Morton , Hugh Dickins , Rik van Riel On 05/14/2012 08:58 PM, ehrhardt@linux.vnet.ibm.com wrote: > From: Ehrhardt Christian > > From: Christian Ehrhardt > > In an memory overcommitment scneario with KVM I ran into a lot of wiats for > swap. While checking the I/O done on the swap disks I found almost all I/Os > to be done as single page 4k request. Despite the fact that swap in is a > batch of 1< pages written in shrink_page_list. > > [1/2 swap in improvment] > The read patch shows improvements of up to 50% swap throughput, much happier > guest systems and even when running with comparable throughput a lot I/O per > seconds saved leaving resources in the SAN for other consumers. > > [2/2 documentation] > While doing so I also realized that the documentation for > proc/sys/vm/page-cluster is no more matching the code > > [missing patch #3] > I tried to get a similar patch working for swap out in shrink_page_list. And > it worked in functional terms, but the additional mergin was negligible. I think we have already done it. Look at shrink_mem_cgroup_zone which ends up calling shrink_page_list so we already have applied I/O plugging. > Maybe the cond_resched triggers much mor often than I expected, I'm open for > suggestions regarding improving the pagout I/O sizes as well. We could enhance write out by batch like ext4_bio_write_page. > > Kind regards, > Christian Ehrhardt > > > Christian Ehrhardt (2): > swap: allow swap readahead to be merged > documentation: update how page-cluster affects swap I/O > > Documentation/sysctl/vm.txt | 12 ++++++++++-- > mm/swap_state.c | 5 +++++ > 2 files changed, 15 insertions(+), 2 deletions(-) > > -- > 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: email@kvack.org > -- Kind regards, Minchan Kim -- 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: email@kvack.org