From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id 29004280725 for ; Tue, 22 Aug 2017 15:37:17 -0400 (EDT) Received: by mail-pg0-f72.google.com with SMTP id t193so104447372pgc.0 for ; Tue, 22 Aug 2017 12:37:17 -0700 (PDT) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTPS id k5si9187000pgp.450.2017.08.22.12.37.15 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 22 Aug 2017 12:37:16 -0700 (PDT) Date: Tue, 22 Aug 2017 12:37:14 -0700 From: Andi Kleen Subject: Re: [PATCH 1/2] sched/wait: Break up long wake list walk Message-ID: <20170822193714.GZ28715@tassilo.jf.intel.com> References: <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> <20170822190828.GO32112@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: Peter Zijlstra , "Liang, Kan" , Mel Gorman , Mel Gorman , "Kirill A. Shutemov" , Tim Chen , Ingo Molnar , Andrew Morton , Johannes Weiner , Jan Kara , linux-mm , Linux Kernel Mailing List > > Still, generating such a migration storm would be fairly tricky I think. > > Well, Mel seems to have been unable to generate a load that reproduces > the long page waitqueues. And I don't think we've had any other > reports of this either. It could be that it requires a fairly large system. On large systems under load a lot of things take much longer, so what's a tiny window on Mel's system may suddenly be very large, and with much more threads they have a higher chance of bad interactions anyways. We only see it on 4S+ today. But systems are always getting larger, so what's a large system today, will be a normal medium scale system tomorrow. BTW we also collected PT traces for the long hang cases, but it was hard to find a consistent pattern in them. -Andi -- 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/ . Don't email: email@kvack.org