From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754658Ab1LVCPk (ORCPT ); Wed, 21 Dec 2011 21:15:40 -0500 Received: from mga09.intel.com ([134.134.136.24]:20246 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754147Ab1LVCPh (ORCPT ); Wed, 21 Dec 2011 21:15:37 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,352,1309762800"; d="scan'208";a="89154844" Subject: Re: [tip:sched/urgent] sched: Fix select_idle_sibling() regression in selecting an idle SMT sibling From: "Alex,Shi" To: "Siddha, Suresh B" Cc: Peter Zijlstra , "mingo@redhat.com" , "hpa@zytor.com" , "linux-kernel@vger.kernel.org" , "efault@gmx.de" , "tglx@linutronix.de" , "mingo@elte.hu" , "linux-tip-commits@vger.kernel.org" , "Li, Shaohua" , "Chen, Tim C" , "Huang, Ying" In-Reply-To: <1324519393.21294.20.camel@sbsiddha-desk.sc.intel.com> References: <1323978421.1984.244.camel@sbsiddha-desk.sc.intel.com> <1324471944.10752.8.camel@twins> <1324496556.21294.11.camel@sbsiddha-desk.sc.intel.com> <1324517502.17054.174.camel@debian> <1324519393.21294.20.camel@sbsiddha-desk.sc.intel.com> Content-Type: text/plain; charset="UTF-8" Date: Thu, 22 Dec 2011 10:16:01 +0800 Message-ID: <1324520161.17054.190.camel@debian> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2011-12-22 at 10:03 +0800, Siddha, Suresh B wrote: > On Wed, 2011-12-21 at 17:31 -0800, Shi, Alex wrote: > > This patch partly fixed a performance regression that triggered by > > 4dcfe1025b513c2c, but issue still exists. > > So how much was the regression caused by the commit 4dcfe1025b513c2c and > how much did we recover with this fix I posted. If we are talking about > the regression caused by this single commit 4dcfe1025b513c2c, then I > don't know of any other related fixes other than the recent fix we > pushed upstream (ab2789213d224202237292d78aaa0c386c7b28b2). A little complex for the whole thing. on 4 sockets EX machine, 3~5% hackbench thread regression due to 4dcfe can be recovered by ab2789. But on 2 sockets SNB machine, 1024 clients loop netperf TCP-RR has about 9% regression. and your patch seem recover 2~3%. And on a 2 sockets nhm, one of our private benchmark was impact much 20 +% regression. that benchmark just run 4 process, each of process open a thread, and the thread tasks is to locate randomly pages and than read from 4 times/write 1 time data into a page. The ab2789 commit seems no help our benchmark.