From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267522AbUHEACZ (ORCPT ); Wed, 4 Aug 2004 20:02:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267523AbUHEACZ (ORCPT ); Wed, 4 Aug 2004 20:02:25 -0400 Received: from web12823.mail.yahoo.com ([216.136.174.204]:45449 "HELO web12823.mail.yahoo.com") by vger.kernel.org with SMTP id S267522AbUHEACF (ORCPT ); Wed, 4 Aug 2004 20:02:05 -0400 Message-ID: <20040805000205.53959.qmail@web12823.mail.yahoo.com> Date: Wed, 4 Aug 2004 17:02:05 -0700 (PDT) From: Shantanu Goel Subject: Re: [VM PATCH 2.6.8-rc1] Prevent excessive scanning of lower zone To: Andrew Morton Cc: linux-kernel@vger.kernel.org In-Reply-To: <20040722220701.7de4c31f.akpm@osdl.org> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="0-559835686-1091664125=:51903" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --0-559835686-1091664125=:51903 Content-Type: text/plain; charset=us-ascii Content-Id: Content-Disposition: inline Hi Andrew, --- Andrew Morton wrote: > Shantanu Goel wrote: > > > > I emailed this a few weeks back to the list but it > > seems to have gotten lost... > > It came through. I was unable to reproduce the > disproportional scanning > rate on almost exactly the same setup, so I parked > the problem for a while. > > I do agree with the analysis though. The problem > _could_ occur. I dunno > why it happens for you and not for me... > Actually, the analysis turned out to be not entirely correct. I think I have identified the offending code. Please see attached patch. It makes kswapd() skip zones which contain greater than "pages_high" pages. Machine setup is the same as before. 2x2.0Ghz Xeon w/HT, memory 256M (manually pegged). I see this lopsided lower zone scanning on a dual Opteron machine as well. Attached are the kernbench results for stock 2.6.8-rc1 and 2.6.8-rc1 with patch. Thanks, Shantanu __________________________________ Do you Yahoo!? Y! Messenger - Communicate in real time. 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