From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754293Ab3GJDJb (ORCPT ); Tue, 9 Jul 2013 23:09:31 -0400 Received: from ozlabs.org ([203.10.76.45]:48267 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753803Ab3GJDJa (ORCPT ); Tue, 9 Jul 2013 23:09:30 -0400 Date: Wed, 10 Jul 2013 13:09:26 +1000 From: Michael Ellerman To: Peter Zijlstra Cc: Vince Weaver , Vince Weaver , Runzhen Wang , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, paulus@samba.org, acme@redhat.com, mingo@kernel.org, Stephane Eranian , sukadev@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com Subject: Re: [PATCH v2 2/2] perf tools: Make Power7 events available for perf Message-ID: <20130710030926.GD7491@concordia> References: <1372170933-4538-1-git-send-email-runzhen@linux.vnet.ibm.com> <1372170933-4538-3-git-send-email-runzhen@linux.vnet.ibm.com> <20130704125218.GA21134@concordia> <20130704125700.GM18898@dyad.programming.kicks-ass.net> <20130709012952.GA7185@concordia> <20130709081434.GI25631@dyad.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130709081434.GI25631@dyad.programming.kicks-ass.net> 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 Tue, Jul 09, 2013 at 10:14:34AM +0200, Peter Zijlstra wrote: > On Mon, Jul 08, 2013 at 10:24:34PM -0400, Vince Weaver wrote: > > > > So something like they have on ARM? > > > > vince@pandaboard:/sys/bus/event_source/devices$ ls -l > > lrwxrwxrwx 1 root root 0 Jul 8 21:57 ARMv7 Cortex-A9 -> ../../../devices/ARMv7 Cortex-A9 > > lrwxrwxrwx 1 root root 0 Jul 8 21:57 breakpoint -> ../../../devices/breakpoint > > lrwxrwxrwx 1 root root 0 Jul 8 21:57 software -> ../../../devices/software > > lrwxrwxrwx 1 root root 0 Jul 8 21:57 tracepoint -> ../../../devices/tracepoint > > Right so what I remember of the ARM case is that their /proc/cpuinfo isn't > sufficient to identify their PMU. And they don't have a cpuid like instruction > at all. > > > > For the cpu you can obviously just detect what processor you're on with > > > cpuid or whatever, but it's a bit of a hack. And that really doesn't > > > work for non-cpu PMUs. > > > > why is it a hack to use cpuid? > > I agree, for x86 cpuid is perfectly fine, as would /proc/cpuinfo be, I suspect > that just the model number is sufficient in most cases, even for uncore stuff. What about things on PCI? Other strange buses? As long as everything's in /sys then it should be _possible_ for userspace to work out what's what, but it's going to end up with a bunch of detection logic and heuristics in the library. At which point you've just rewritten libpfm4. cheers