From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx178.postini.com [74.125.245.178]) by kanga.kvack.org (Postfix) with SMTP id 5A6936B0082 for ; Thu, 17 May 2012 16:23:26 -0400 (EDT) Date: Thu, 17 May 2012 13:23:24 -0700 From: Andrew Morton Subject: Re: [PATCH] mm: consider all swapped back pages in used-once logic Message-Id: <20120517132324.e9bf9fc8.akpm@linux-foundation.org> In-Reply-To: <20120517121049.GA11018@tiehlicka.suse.cz> References: <1337246033-13719-1-git-send-email-mhocko@suse.cz> <20120517022412.9175f604.akpm@linux-foundation.org> <20120517121049.GA11018@tiehlicka.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Mel Gorman , Minchan Kim , KAMEZAWA Hiroyuki , Rik van Riel On Thu, 17 May 2012 14:10:49 +0200 Michal Hocko wrote: > > > This patch fixes a regression introduced by this commit for heavy shmem > > > > A performance regression, specifically. > > > > Are you able to quantify it? > > The customer's workload is shmem backed database (80% of RAM) and > they are measuring transactions/s with an IO in the background (20%). > Transactions touch more or less random rows in the table. > The rate goes down drastically when we start swapping out memory. > > Numbers are more descriptive (without the patch is 100%, with 5 > representative runs) > Average rate 315.83% > Best rate 131.76% > Worst rate 641.25% > > Standard deviation (calibrated to average) is ~4% while without the > patch we are at 62.82%. > The big variance without the patch is caused by the excessive swapping > which doesn't occur with the patch applied. > > * Worst run (100%) compared to a random run with the patch > pgpgin pswpin pswpout pgmajfault > 1.58% 0.00% 0.01% 0.22% > > Average size of the LRU lists: > nr_inactive_anon nr_active_anon nr_inactive_file nr_active_file > 52.91% 7234.72% 249.39% 126.64% > > * Best run > pgpgin pswpin pswpout pgmajfault > 3.37% 0.00% 0.11% 0.39% > > nr_inactive_anon nr_active_anon nr_inactive_file nr_active_file > 49.85% 3868.74% 175.03% 121.27% I turned the above into this soundbite: : The customer's workload is shmem backed database (80% of RAM) and they are : measuring transactions/s with an IO in the background (20%). Transactions : touch more or less random rows in the table. Total runtime was : approximately tripled by commit 64574746 and this patch restores the : previous throughput levels. Was that truthful? -- 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