From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756146Ab0CKTPA (ORCPT ); Thu, 11 Mar 2010 14:15:00 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:51978 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755315Ab0CKTO6 (ORCPT ); Thu, 11 Mar 2010 14:14:58 -0500 Date: Thu, 11 Mar 2010 20:14:41 +0100 From: Ingo Molnar To: Corey Ashford Cc: LKML , Peter Zijlstra , Frederic Weisbecker , Steven Rostedt Subject: Re: [RFC] [PATCH 1/1] perf: add support for arch-dependent symbolic event names to "perf stat" Message-ID: <20100311191441.GA7593@elte.hu> References: <4B8F1B58.5000702@linux.vnet.ibm.com> <4B8FFE55.5070008@linux.vnet.ibm.com> <20100311124608.GG31354@elte.hu> <4B993AAF.9050507@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B993AAF.9050507@linux.vnet.ibm.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=none autolearn=no SpamAssassin version=3.2.5 _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Corey Ashford wrote: > On 3/11/2010 4:46 AM, Ingo Molnar wrote: > [snip] > >If you want extensible events you can already do it by providing an ftrace > >tracepoint event via TRACE_EVENT. They are easy to add and ad-hoc, and are > >supported throughout by perf. > > Is TRACE_EVENT an appropriate way to add hardware-specific counter > events? I will look into this. Thanks for the pointer. > > > > >That could be librarized further by providing an /eventfs or /proc/events > >interface to enumerate them. > > We can enumerate events this way, but there are other aspects to > events than just their names (see below). > > > > >Or if you want to extend the perf events namespace ABI you can send patches > >for that as well. (It's not a big issue if a particular event is currently > >only supported on Power for example - as long as you make a good effort naming > >and structuring it in a reasonably generic way.) > > I'm not sure how that would work. The issue I am trying to solve > here is that Power arch chips have a large number of very > hardware-specific events that are not generalizable. Many of these > events not only have names, but other user-configurable bits as well > that select or narrow the scope of which exact events are recorded. > This issue is dealt with nicely in libpfm4, as it has mechanisms for > parsing event names and attributes (aka modifiers or unit masks), > and then produces a usable config field for the perf_events_attr > struct. > > Should I take it from the above that you are completely against the > idea of using an external library for hardware-specific event and > attribute naming? Could you give a few relevant examples of events in question, and the kind of configurability/attributes they have on Power? Thanks, Ingo