From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx159.postini.com [74.125.245.159]) by kanga.kvack.org (Postfix) with SMTP id 3E3CF6B0081 for ; Mon, 21 May 2012 03:51:32 -0400 (EDT) Received: from /spool/local by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 21 May 2012 08:51:30 +0100 Received: from d06av05.portsmouth.uk.ibm.com (d06av05.portsmouth.uk.ibm.com [9.149.37.229]) by d06nrmr1806.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q4L7pSxn2150612 for ; Mon, 21 May 2012 08:51:28 +0100 Received: from d06av05.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av05.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q4L7pSVA007928 for ; Mon, 21 May 2012 01:51:28 -0600 Message-ID: <4FB9F3FF.7030709@linux.vnet.ibm.com> Date: Mon, 21 May 2012 09:51:27 +0200 From: Christian Ehrhardt 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> <4FB1E2A0.9050900@kernel.org> In-Reply-To: <4FB1E2A0.9050900@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: linux-mm@kvack.org, axboe@kernel.dk, Andrew Morton , Hugh Dickins , Rik van Riel [...] >> [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. > I saw that code and it is part of the kernel I used to test my patches. But despite that code and my additional experiments of plug/unplug in shrink_page_list the effective I/O size of swap write stays at almost 4k. Thereby so far I can tell you that the plugs in shrink_page_list and shrink_mem_cgroup_zone aren't sufficient - at least for my case. You saw the blocktrace summaries in my first mail, an excerpt of a write submission stream looks like that: 94,4 10 465 0.023520923 116 A W 28868648 + 8 <- (94,5) 28868456 94,5 10 466 0.023521173 116 Q W 28868648 + 8 [kswapd0] 94,5 10 467 0.023522048 116 G W 28868648 + 8 [kswapd0] 94,5 10 468 0.023522235 116 P N [kswapd0] 94,5 10 469 0.023759892 116 I W 28868648 + 8 ( 237844) [kswapd0] 94,5 10 470 0.023760079 116 U N [kswapd0] 1 94,5 10 471 0.023760360 116 D W 28868648 + 8 ( 468) [kswapd0] 94,4 10 472 0.023891235 116 A W 28868656 + 8 <- (94,5) 28868464 94,5 10 473 0.023891454 116 Q W 28868656 + 8 [kswapd0] 94,5 10 474 0.023892110 116 G W 28868656 + 8 [kswapd0] 94,5 10 475 0.023944610 116 I W 28868656 + 8 ( 52500) [kswapd0] 94,5 10 476 0.023944735 116 U N [kswapd0] 1 94,5 10 477 0.023944892 116 D W 28868656 + 8 ( 282) [kswapd0] 94,5 16 19 0.024023192 16033 C W 28868648 + 8 ( 262832) [0] 94,5 24 37 0.024196752 14526 C W 28868656 + 8 ( 251860) [0] [...] But we can split this discussion from my other two patches and I would be happy to provide my test environment for further tests if there are new suggestions/patches/... >> 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. > Do you mean the changes brought by "bd2d0210 ext4: use bio layer instead of buffer layer in mpage_da_submit_io" ? -- GrA 1/4 sse / regards, Christian Ehrhardt IBM Linux Technology Center, System z Linux Performance -- 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