Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756102Ab3EATNt (ORCPT ); Wed, 1 May 2013 15:13:49 -0400 Received: from one.firstfloor.org ([193.170.194.197]:60992 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755349Ab3EATNn (ORCPT ); Wed, 1 May 2013 15:13:43 -0400 Date: Wed, 1 May 2013 21:13:42 +0200 From: Andi Kleen To: Stephane Eranian Cc: Peter Zijlstra , Andi Kleen , "mingo@elte.hu" , LKML Subject: Re: [PATCH] perf, x86: Add workaround for MEM_*_RETIRED errata BV98 Message-ID: <20130501191342.GH17814@two.firstfloor.org> References: <1367261108-9567-1-git-send-email-andi@firstfloor.org> <20130501090718.GA28253@dyad.programming.kicks-ass.net> <20130501111219.GF28253@dyad.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 951 Lines: 25 > Unfortunately, Andi's patch fails to correct the problem though > it is the right approach. As he said, the problem is unfortunately perf stat -a / record -a / top will work. The case it doesn't fix is per thread when the other sibling is not running a counter. Essentially with the patch you may still get under-counting on these specific events if they run per thread (or are really unlucky in multiplexing), but never over-counting on anything. In the past Ingo's guidance was to focus on the most common use cases, which I think this patch does. It would be possible to fix the per thread mode too, but it would need quite a bit of new infrastructure and I have doubts that's worth it. -Andi -- 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/