From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754714AbbLKOXv (ORCPT ); Fri, 11 Dec 2015 09:23:51 -0500 Received: from foss.arm.com ([217.140.101.70]:33727 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754519AbbLKOXt (ORCPT ); Fri, 11 Dec 2015 09:23:49 -0500 Date: Fri, 11 Dec 2015 14:23:36 +0000 From: Mark Rutland To: Peter Zijlstra Cc: Alexander Shishkin , Ingo Molnar , linux-kernel@vger.kernel.org, vince@deater.net, eranian@google.com, Arnaldo Carvalho de Melo , Mathieu Poirier Subject: Re: [PATCH v0 3/5] perf: Introduce instruction trace filtering Message-ID: <20151211142335.GC20666@leverpostej> References: <1449840998-29902-1-git-send-email-alexander.shishkin@linux.intel.com> <1449840998-29902-4-git-send-email-alexander.shishkin@linux.intel.com> <20151211140201.GQ6356@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151211140201.GQ6356@twins.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 Fri, Dec 11, 2015 at 03:02:01PM +0100, Peter Zijlstra wrote: > On Fri, Dec 11, 2015 at 03:36:36PM +0200, Alexander Shishkin wrote: > > > The pmu driver interface basically adds an extra callback to the > > pmu driver structure, which validates the filter configuration proposed > > by the user against what the hardware is actually capable of doing > > and translates it into something that pmu::start can program into > > hardware. > > > @@ -388,12 +393,38 @@ struct pmu { > > void (*free_aux) (void *aux); /* optional */ > > > > /* > > + * Validate instruction tracing filters: make sure hw supports the > > + * requested configuration and number of filters. > > + * > > + * Configure instruction tracing filters: translate hw-agnostic filter > > + * into hardware configuration in event::hw::itrace_filters > > + */ > > + int (*itrace_filter_setup) (struct perf_event *event); /* optional */ > > + > > + /* > > * Filter events for PMU-specific reasons. > > */ > > int (*filter_match) (struct perf_event *event); /* optional */ > > }; > > Any reason you cannot use pmu::filter_match ? Maybe I've misunderstood your point, but the two seem quite different. We introduced pmu::filter_match to apply a SW filter each time we installed events from a context. We use that on ARM to avoid programming big events into little cores and vice-versa. As far as I can see, itrace_filter_setup is closer in operation to event_init. It can fail at configuration time (long before scheduling events to cores), and leaves the actual filtering to the HW. Thanks, Mark.