From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756633Ab0KJPSV (ORCPT ); Wed, 10 Nov 2010 10:18:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:21439 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756199Ab0KJPSU (ORCPT ); Wed, 10 Nov 2010 10:18:20 -0500 Date: Wed, 10 Nov 2010 16:17:50 +0100 From: Jiri Olsa To: Frederic Weisbecker Cc: Ingo Molnar , Christoph Hellwig , rostedt@goodmis.org, andi@firstfloor.org, lwoodman@redhat.com, linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: [PATCH 1/2] tracing,mm - add kernel pagefault tracepoint for x86 & x86_64 Message-ID: <20101110151750.GA11541@jolsa.brq.redhat.com> References: <1289390172-9730-1-git-send-email-jolsa@redhat.com> <1289390172-9730-2-git-send-email-jolsa@redhat.com> <20101110132954.GA2101@infradead.org> <20101110134436.GD1949@jolsa.brq.redhat.com> <20101110135244.GA31638@elte.hu> <20101110150021.GA5750@nowhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101110150021.GA5750@nowhere> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 10, 2010 at 04:00:25PM +0100, Frederic Weisbecker wrote: > On Wed, Nov 10, 2010 at 02:52:44PM +0100, Ingo Molnar wrote: > > > > * Jiri Olsa wrote: > > > > > On Wed, Nov 10, 2010 at 08:29:54AM -0500, Christoph Hellwig wrote: > > > > On Wed, Nov 10, 2010 at 12:56:11PM +0100, Jiri Olsa wrote: > > > > > + TP_printk("task=%lx, address=%lx, regs=%lx", > > > > > + (unsigned long)__entry->task, (unsigned long)__entry->address, > > > > > + __entry->regs) > > > > > > > > How exactly do you use the information in this trace point? Especially > > > > the undecoded pt_regs doesn't seem very useful to me at all. > > > > > > agreed, the registers pointer are not very useful in the trace file output, > > > and could be taken away.. just wanted to be complete I guess > > > > > > but I believe they are useful when you register the mm_kernel_pagefault > > > tracepoint and process the information by yourself > > > > That would be expressed in a better and more generic fashion via adding > > PERF_SAMPLE_REGS to perf_event_sample_format, and add a ptregs dump in > > kernel/perf_event.c, perf_output_sample(). That way any tracepoint can request a > > (user-space)ptregs state snapshot, not just the pagefault ones. > > > > Thanks, > > > > Ingo > > > We are going to have that with the dwarf based callchain patchset. I'm cooking > this. > > Thanks. > I guess I can take the regs out then.. would that patch be acceptable afterwards..? thanks, jirka