From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f175.google.com (mail-we0-f175.google.com [74.125.82.175]) by kanga.kvack.org (Postfix) with ESMTP id E2F2B6B003D for ; Fri, 20 Dec 2013 06:18:23 -0500 (EST) Received: by mail-we0-f175.google.com with SMTP id t60so2283598wes.6 for ; Fri, 20 Dec 2013 03:18:23 -0800 (PST) Received: from mail-ee0-x22a.google.com (mail-ee0-x22a.google.com [2a00:1450:4013:c00::22a]) by mx.google.com with ESMTPS id hm7si3657869wib.39.2013.12.20.03.18.22 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 20 Dec 2013 03:18:22 -0800 (PST) Received: by mail-ee0-f42.google.com with SMTP id e53so977494eek.15 for ; Fri, 20 Dec 2013 03:18:22 -0800 (PST) Date: Fri, 20 Dec 2013 12:18:18 +0100 From: Ingo Molnar Subject: Re: [PATCH 0/4] Fix ebizzy performance regression due to X86 TLB range flush v2 Message-ID: <20131220111818.GA23349@gmail.com> References: <20131215155539.GM11295@suse.de> <20131216102439.GA21624@gmail.com> <20131216125923.GS11295@suse.de> <20131216134449.GA3034@gmail.com> <20131217092124.GV11295@suse.de> <20131217110051.GA27701@gmail.com> <20131219142405.GM11295@suse.de> <20131219164925.GA29546@gmail.com> <20131220111303.GZ11295@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131220111303.GZ11295@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Linus Torvalds , Alex Shi , Thomas Gleixner , Andrew Morton , Fengguang Wu , H Peter Anvin , Linux-X86 , Linux-MM , LKML , Peter Zijlstra * Mel Gorman wrote: > On Thu, Dec 19, 2013 at 05:49:25PM +0100, Ingo Molnar wrote: > > > > * Mel Gorman wrote: > > > > > [...] > > > > > > Because we lack data on TLB range flush distributions I think we > > > should still go with the conservative choice for the TLB flush > > > shift. The worst case is really bad here and it's painfully obvious > > > on ebizzy. > > > > So I'm obviously much in favor of this - I'd in fact suggest > > making the conservative choice on _all_ CPU models that have > > aggressive TLB range values right now, because frankly the testing > > used to pick those values does not look all that convincing to me. > > I think the choices there are already reasonably conservative. I'd > be reluctant to support merging a patch that made a choice on all > CPU models without having access to the machines to run tests on. I > don't see the Intel people volunteering to do the necessary testing. So based on this thread I lost confidence in test results on all CPU models but the one you tested. I see two workable options right now: - We turn the feature off on all other CPU models, until someone measures and tunes them reliably. or - We make all tunings that are more aggressive than yours to match yours. In the future people can measure and argue for more aggressive tunings. Thanks, Ingo -- 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