Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758080Ab3G3IiO (ORCPT ); Tue, 30 Jul 2013 04:38:14 -0400 Received: from merlin.infradead.org ([205.233.59.134]:40077 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751601Ab3G3IiL (ORCPT ); Tue, 30 Jul 2013 04:38:11 -0400 Date: Tue, 30 Jul 2013 10:37:58 +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: <20130730083758.GH3008@twins.programming.kicks-ass.net> References: <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> <20130628095828.GG29209@dyad.programming.kicks-ass.net> <20130708081919.GV23916@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: 1250 Lines: 26 On Tue, Jul 30, 2013 at 10:02:01AM +0200, Stephane Eranian wrote: > > Ahh. We don't put the useful bits in the mmap event; we'll need to fix > > that too then ;-) > > > > Doing so is going to be a bit of a bother since we use the tail of > > PERF_RECORD_MMAP for filenames and thus aren't particularly extensible. > > > > This would mean doing something like PERF_RECORD_MMAP2 and some means > > for userspace to requrest the new events instead of the old one. > > > Tracking mmaps even for shmat() won't cover the paging cases. When you page a > page back in, it most likely gets a different physical page. How would > we track that > case too using the same approach? It doesn't matter. Even if a page ends up being a different physical page, it will always be the same sb:inode:pgoffset. You should be able to always uniquely identify a (shared) page by that triplet. So if we create a net MMAP record that includes the device (substitute for the superblock) and inode information we should be good. -- 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/