Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754610Ab0BJKxU (ORCPT ); Wed, 10 Feb 2010 05:53:20 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:53371 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753908Ab0BJKxT (ORCPT ); Wed, 10 Feb 2010 05:53:19 -0500 Subject: Re: [RFC perf,x86] P4 PMU early draft From: Peter Zijlstra To: Cyrill Gorcunov Cc: Ingo Molnar , Stephane Eranian , Frederic Weisbecker , Don Zickus , LKML In-Reply-To: References: <20100208184504.GB5130@lenovo> <20100209041739.GA11280@elte.hu> <20100209223909.GE5068@lenovo> <1265796732.11509.260.camel@laptop> Content-Type: text/plain; charset="UTF-8" Date: Wed, 10 Feb 2010 11:52:55 +0100 Message-ID: <1265799175.11509.271.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1144 Lines: 27 On Wed, 2010-02-10 at 13:38 +0300, Cyrill Gorcunov wrote: > > I'd try BUG_ON(cpu != smp_processor_id()) and scrap passing that cpu > > thing around. > > > > no, i need cpu to find out if event has migrated from other thread and > then i switch > some thread dependant flags in hw::config (ie escr and cccr), or i > miss something and events in one cpu just can't migrate to another > cpu? Well, if we validate that cpu == smp_processor_id() (looking at kernel/perf_event.c that does indeed seem true for hw_perf_group_sched_in() -- which suggests we should simply remove that cpu argument), and that cpu will stay constant throughout the whole callchain (it does, its a local variable), we can remove it and substitute smp_processor_id(), right? As to migration of the event, its tied to a task, we're now installing the event for a task it wouldn't make sense to allow that to be preemptible. -- 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/