Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752637AbYJFG7k (ORCPT ); Mon, 6 Oct 2008 02:59:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751327AbYJFG7c (ORCPT ); Mon, 6 Oct 2008 02:59:32 -0400 Received: from www.tglx.de ([62.245.132.106]:57972 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751262AbYJFG7c (ORCPT ); Mon, 6 Oct 2008 02:59:32 -0400 Date: Mon, 6 Oct 2008 08:59:25 +0200 (CEST) From: Thomas Gleixner To: "Zhang, Yanmin" cc: LKML Subject: Re: aim7 47% regression with 2.6.27-rc8 In-Reply-To: <1223269135.1685.11.camel@ymzhang> Message-ID: References: <1223269135.1685.11.camel@ymzhang> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1728 Lines: 41 On Mon, 6 Oct 2008, Zhang, Yanmin wrote: > Comparing with 2.6.27-rc8, aim7 result has about 47% regression with 2.6.27-rc8 on > my 16-core tigerton and 8 core+HyperThreading x86_64 machine. > > I bisected it down to patch: > > 302745699c1b675b5d2a1af87271de10e4d96b6a is first bad commit > commit 302745699c1b675b5d2a1af87271de10e4d96b6a > Author: Thomas Gleixner > Date: Mon Sep 22 19:02:25 2008 +0200 > > clockevents: check broadcast device not tick device > > Impact: Possible hang on CPU online observed on AMD C1E machines. > > The broadcast setup code looks at the mode of the tick device to > determine whether it needs to be shut down or setup. This is wrong > when the broadcast mode is set to one shot already. This can happen > when a CPU is brought online as it goes through the periodic setup > first. > > The problem went unnoticed as sane systems do not call into that code > before the switch to one shot for the clock event device happens. > The AMD C1E idle routine switches over immediately and thereby shuts > down the just setup device before the first interrupt happens. > > > After I reverted the patch against 2.6.27-rc8, the regression disappears. > It's interesting that the regression doesn't exist on 8-core stoakley. There is a fixup patch for this one after rc8. 07454bfff151d2465ada809bbaddf3548cc1097c Can you check with this one applied please ? Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/