Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932772AbdHWUza (ORCPT ); Wed, 23 Aug 2017 16:55:30 -0400 Received: from mga04.intel.com ([192.55.52.120]:27532 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932407AbdHWUzS (ORCPT ); Wed, 23 Aug 2017 16:55:18 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,417,1498546800"; d="scan'208";a="893482637" From: "Liang, Kan" To: Linus Torvalds , Tim Chen CC: Mel Gorman , Mel Gorman , "Kirill A. Shutemov" , Peter Zijlstra , Ingo Molnar , Andi Kleen , Andrew Morton , "Johannes Weiner" , Jan Kara , linux-mm , Linux Kernel Mailing List Subject: RE: [PATCH 1/2] sched/wait: Break up long wake list walk Thread-Topic: [PATCH 1/2] sched/wait: Break up long wake list walk Thread-Index: AQHTFWNBYSKZKyu5OE6Y+fM96SxNwqKEIDEAgASaOPD//398AIAAsKCA//+X4wCAAQZZgIAAplUA//+BiwAAFSW90P//ia2AgAASl4CAAAVjAIAEq10A//91k2D//XJ4kIAEpo4A//9gzkAAGOTugP/+TzqA//0MIYD/+fF1AP/zMXwg Date: Wed, 23 Aug 2017 20:55:15 +0000 Message-ID: <37D7C6CF3E00A74B8858931C1DB2F0775378EC56@shsmsx102.ccr.corp.intel.com> References: <37D7C6CF3E00A74B8858931C1DB2F077537879BB@SHSMSX103.ccr.corp.intel.com> <20170818144622.oabozle26hasg5yo@techsingularity.net> <37D7C6CF3E00A74B8858931C1DB2F07753787AE4@SHSMSX103.ccr.corp.intel.com> <20170818185455.qol3st2nynfa47yc@techsingularity.net> <20170821183234.kzennaaw2zt2rbwz@techsingularity.net> <37D7C6CF3E00A74B8858931C1DB2F07753788B58@SHSMSX103.ccr.corp.intel.com> <37D7C6CF3E00A74B8858931C1DB2F0775378A24A@SHSMSX103.ccr.corp.intel.com> <37D7C6CF3E00A74B8858931C1DB2F0775378A377@SHSMSX103.ccr.corp.intel.com> <37D7C6CF3E00A74B8858931C1DB2F0775378A8AB@SHSMSX103.ccr.corp.intel.com> <6e8b81de-e985-9222-29c5-594c6849c351@linux.intel.com> In-Reply-To: Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiYTRlMDhmOWYtYTM5OS00NTIyLTljN2EtMWMyOTdkNzI0NTY0IiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX0lDIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE2LjUuOS4zIiwiVHJ1c3RlZExhYmVsSGFzaCI6IkJPMVpzbUNiNHV1Y1dyN2h5UDBTRUc2ZElFRnpEOGk3WEZIYkpuZENHVEU9In0= x-ctpclassification: CTP_IC dlp-product: dlpe-windows dlp-version: 10.0.102.7 dlp-reaction: no-action x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id v7NKtXh8010912 Content-Length: 1417 Lines: 44 > > On Wed, Aug 23, 2017 at 8:58 AM, Tim Chen > wrote: > > > > Will you still consider the original patch as a fail safe mechanism? > > I don't think we have much choice, although I would *really* want to get this > root-caused rather than just papering over the symptoms. > > Maybe still worth testing that "sched/numa: Scale scan period with tasks in > group and shared/private" patch that Mel mentioned. The patch doesn’t help on our load. Thanks, Kan > > In fact, looking at that patch description, it does seem to match this particular > load a lot. Quoting from the commit message: > > "Running 80 tasks in the same group, or as threads of the same process, > results in the memory getting scanned 80x as fast as it would be if a > single task was using the memory. > > This really hurts some workloads" > > So if 80 threads causes 80x as much scanning, a few thousand threads might > indeed be really really bad. > > So once more unto the breach, dear friends, once more. > > Please. > > The patch got applied to -tip as commit b5dd77c8bdad, and can be > downloaded here: > > > https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=b5dd > 77c8bdada7b6262d0cba02a6ed525bf4e6e1 > > (Hmm. It says it's cc'd to me, but I never noticed that patch simply because it > was in a big group of other -tip commits.. Oh well). > > Linus