Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756071Ab0KKMGT (ORCPT ); Thu, 11 Nov 2010 07:06:19 -0500 Received: from canuck.infradead.org ([134.117.69.58]:41097 "EHLO canuck.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755623Ab0KKMGS convert rfc822-to-8bit (ORCPT ); Thu, 11 Nov 2010 07:06:18 -0500 Subject: Re: [Questions] How to run 'perf top' on ARM to profile kernel functions with modules loaded From: Peter Zijlstra To: Jamie Iles Cc: Ming Lei , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , Russell King , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org In-Reply-To: <20101111091733.GA2929@pulham.picochip.com> References: <20101111091733.GA2929@pulham.picochip.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Thu, 11 Nov 2010 13:06:16 +0100 Message-ID: <1289477176.2084.64.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1174 Lines: 25 On Thu, 2010-11-11 at 09:17 +0000, Jamie Iles wrote: > On Thu, Nov 11, 2010 at 03:52:07PM +0800, Ming Lei wrote: > > 2010/11/11 Ming Lei : > > > Hi, > > > > > > 'perf top' can't display any functions when modules are loaded on ARM. > > > > Sorry, should be can't display any kernel functions when modules are loaded > > on ARM. > I've noticed this myself and I spent a bit of time looking into it last week > but didn't get too far. I did wonder if it was something to do with the map > fixups after loading the modules. If you look at the raw events after a perf > record with 'perf report -D' then the last module has a size that takes it to > 0xFFFFFFFF which overlaps with the rest of the kernel symbols. > > On x86 it looks like the modules are loaded after the kernel image in VM > unlike ARM. Order shouldn't matter, but that overlap is very likely what kills it. That module size is buggy. -- 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/