Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755263Ab3F1J7N (ORCPT ); Fri, 28 Jun 2013 05:59:13 -0400 Received: from merlin.infradead.org ([205.233.59.134]:46878 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755043Ab3F1J7M (ORCPT ); Fri, 28 Jun 2013 05:59:12 -0400 Date: Fri, 28 Jun 2013 11:58:28 +0200 From: Peter Zijlstra To: Stephane Eranian Cc: Ingo Molnar , LKML , "mingo@elte.hu" , "ak@linux.intel.com" , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim Subject: Re: [PATCH 0/8] perf: add ability to sample physical data addresses Message-ID: <20130628095828.GG29209@dyad.programming.kicks-ass.net> References: <1371824448-7306-1-git-send-email-eranian@google.com> <20130624084338.GI28407@twins.programming.kicks-ass.net> <20130625104700.GZ28407@twins.programming.kicks-ass.net> <20130625105123.GA13649@gmail.com> <20130626103303.GB28407@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1098 Lines: 23 On Wed, Jun 26, 2013 at 09:10:50PM +0200, Stephane Eranian wrote: > After more investigation with the author of the false sharing > detection tool, I think > that if the mapping changes, it is okay. The tool can detect this and > drop the analysis > at that address. So as long as we can flag the mapping change, we are > okay. Hopefully, > it does not occur frequently. If so, then I think there are bigger > issues to fix on the system > than false sharing. But if you index everything using dev:inode:offset it doesn't matter if the mapping changes; you're invariant to map placement. And the thing is; we already compute most of that anyway in order to find the code in DSOs, except there we use filename instead of dev:inode. However if there were means to open files using dev:inode that might actually be more reliable than using the filename. -- 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/