Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753917AbZFXMf3 (ORCPT ); Wed, 24 Jun 2009 08:35:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751058AbZFXMfR (ORCPT ); Wed, 24 Jun 2009 08:35:17 -0400 Received: from 124x34x33x190.ap124.ftth.ucom.ne.jp ([124.34.33.190]:34624 "EHLO master.linux-sh.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750720AbZFXMfR (ORCPT ); Wed, 24 Jun 2009 08:35:17 -0400 Date: Wed, 24 Jun 2009 21:34:16 +0900 From: Paul Mundt To: Martin Schwidefsky Cc: Ingo Molnar , linux-kernel Subject: Re: register_timer_hook use in arch/sh/oprofile Message-ID: <20090624123416.GB9510@linux-sh.org> Mail-Followup-To: Paul Mundt , Martin Schwidefsky , Ingo Molnar , linux-kernel References: <20090624131104.705c828d@skybase> <20090624112929.GB2079@linux-sh.org> <20090624142828.7c6a2337@skybase> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090624142828.7c6a2337@skybase> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1631 Lines: 39 On Wed, Jun 24, 2009 at 02:28:28PM +0200, Martin Schwidefsky wrote: > On Wed, 24 Jun 2009 20:29:29 +0900 > Paul Mundt wrote: > > No. oprofile_timer_init() is only entered if the performance counters > > fail to register in the SH7750 case, so there is only one timer hook user > > at a time: > > > > static int __init oprofile_init(void) > > { > > int err; > > > > err = oprofile_arch_init(&oprofile_ops); > > > > if (err < 0 || timer) { > > printk(KERN_INFO "oprofile: using timer interrupt.\n"); > > oprofile_timer_init(&oprofile_ops); > > } > > ... > > Oh, I see. That is the reason why the s390 version of > oprofile_arch_init returns -ENODEV. It does so to trigger the fallback > to the timer_hook. That should work for sh as well, no? > It would, yes, but it would also disable access to the SH7750 counters at the same time, so we don't really want to do that. The sh7750 counters are more like timer based profiling with some extra events that can be set and read, so reverting to oprofile_timer_init() would reduce functionality. My current plan is to migrate things over to the perf_counter API and annoy Ingo with my interrupt deprived counters ;-) Given that hrtimers are already generically supported there, it should tie in much cleaner there than in the oprofile case at least. -- 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/