Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934318Ab1CXUy6 (ORCPT ); Thu, 24 Mar 2011 16:54:58 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:37465 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933904Ab1CXUyz (ORCPT ); Thu, 24 Mar 2011 16:54:55 -0400 Date: Thu, 24 Mar 2011 21:54:22 +0100 From: Ingo Molnar To: Eric Dumazet Cc: Jack Steiner , Jan Beulich , Borislav Petkov , Peter Zijlstra , Nick Piggin , "x86@kernel.org" , Thomas Gleixner , Andrew Morton , Linus Torvalds , Ingo Molnar , tee@sgi.com, Nikanth Karthikesan , "linux-kernel@vger.kernel.org" , "H. Peter Anvin" Subject: Re: [PATCH RFC] x86: avoid atomic operation in test_and_set_bit_lock if possible Message-ID: <20110324205422.GB2393@elte.hu> References: <201103241026.01624.knikanth@suse.de> <20110324085647.GI30812@elte.hu> <20110324145221.GC31194@aftab> <4D8B83DA02000078000381DE@vpn.id2.novell.com> <20110324173020.GA26761@sgi.com> <20110324200010.GB7957@elte.hu> <1300999682.2714.23.camel@edumazet-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1300999682.2714.23.camel@edumazet-laptop> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1370 Lines: 50 * Eric Dumazet wrote: > Le jeudi 24 mars 2011 ? 21:00 +0100, Ingo Molnar a ?crit : > > > One good way to see cache bounces is to run a misses/accesses ratio profile: > > > > perf top -e cache-misses -e cache-references --count-filter 10 > > > > Oh well , something must be broken... > > "perf top" is working here, but if I use any "-e ...." argument, it > fails : > > # perf top -e cache-misses > > Error: sys_perf_event_open() syscall returned with 2 (No such file or directory). > /bin/dmesg may provide additional information. > > Fatal: No CONFIG_PERF_EVENTS=y kernel support configured? > > # grep PERF_EVENTS .config > CONFIG_HAVE_PERF_EVENTS=y > CONFIG_PERF_EVENTS=y > CONFIG_HAVE_PERF_EVENTS_NMI=y > > Nothing in dmesg... > > uname -a > Linux ed001 2.6.38-08165-g2712750-dirty #517 SMP Thu Mar 24 21:31:00 CET 2011 i686 i686 i386 GNU/Linux Does it work better if you run it as root? To easiest way to debug as user is to do: echo -1 > /proc/sys/kernel/perf_event_paranoid and to put this into /etc/sysctl.conf: kernel.perf_event_paranoid = -1 Thanks, Ingo -- 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/