Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935452Ab0KQT5M (ORCPT ); Wed, 17 Nov 2010 14:57:12 -0500 Received: from canuck.infradead.org ([134.117.69.58]:37933 "EHLO canuck.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935187Ab0KQT5K convert rfc822-to-8bit (ORCPT ); Wed, 17 Nov 2010 14:57:10 -0500 Subject: Re: [RFC][PATCH] perf: sysfs type id From: Peter Zijlstra To: Corey Ashford Cc: Stephane Eranian , LKML , Ingo Molnar , Lin Ming , "robert.richter" , fweisbec , paulus , Greg Kroah-Hartman , Kay Sievers , "H. Peter Anvin" In-Reply-To: <4CE43153.2070206@linux.vnet.ibm.com> References: <1289339119.2191.92.camel@laptop> <1289398207.2191.117.camel@laptop> <1289398763.2191.121.camel@laptop> <1289421164.2084.56.camel@laptop> <1289423135.2084.63.camel@laptop> <4CE33F86.7040403@linux.vnet.ibm.com> <1289993128.2109.714.camel@laptop> <4CE43153.2070206@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Wed, 17 Nov 2010 20:57:14 +0100 Message-ID: <1290023834.2109.1240.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: 2103 Lines: 47 On Wed, 2010-11-17 at 11:47 -0800, Corey Ashford wrote: > > This is an interesting approach, though for the IBM WSP (aka PowerEN) > chip, the config_format would have to be at a deeper level than the PMU, > because the modifiers that affect the event, vary from event to event. > Either that or you'd have to provide a complex union structure. Eew.. how uhm creative ;-), yeah, not quite sure how to deal with that, I wasn't planning to make a directory for each event, just a single file with the u64 in it. > However, above you say that you want to have "a few frequently > used/common events". I thought that was the job of the perf "generic > events". My understanding was that the sysfs tree was the solution for > all events, including arch-specific, and seldom-used events. My intent for the sysfs bits is to replace all the static stuff encoded in PERF_TYPE_ and PERF_COUNT_ because it simply doesn't extend to a much more dynamic world. And GPUs/DSPs might have radically different common events than CPUs do. Doing exhaustive lists in sysfs is simply going to waste tons of memory for no real gain. > Ingo > pushed back on a user-space library solution (like libpfm4) because he > wanted event info in sysfs (or some other mechanism by which the kernel > could expose event info to user space). I can't fully remember the details of that discussion. > If there is going to be no place in sysfs for arch-specific events, I'll > want to start pushing for perf to be able to use a user space library again. > > How about a compromise position: all of the arch-specific events are > exposed to user space via sysfs iff some CONFIG_* variable to set to > true. Something like CONFIG_EXPOSE_ALL_HW_PERF_EVENTS_IN_SYSFS. > This way you would only use all that memory when it's explicitly > configured in. Ingo, any opinions? -- 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/