Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757381AbZFZH1t (ORCPT ); Fri, 26 Jun 2009 03:27:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752859AbZFZH1m (ORCPT ); Fri, 26 Jun 2009 03:27:42 -0400 Received: from 124x34x33x190.ap124.ftth.ucom.ne.jp ([124.34.33.190]:55389 "EHLO master.linux-sh.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752690AbZFZH1m (ORCPT ); Fri, 26 Jun 2009 03:27:42 -0400 Date: Fri, 26 Jun 2009 16:26:39 +0900 From: Paul Mundt To: Ingo Molnar Cc: Peter Zijlstra , Martin Schwidefsky , linux-kernel Subject: Re: register_timer_hook use in arch/sh/oprofile Message-ID: <20090626072638.GA21610@linux-sh.org> Mail-Followup-To: Paul Mundt , Ingo Molnar , Peter Zijlstra , Martin Schwidefsky , linux-kernel References: <20090624131104.705c828d@skybase> <20090624112929.GB2079@linux-sh.org> <20090624142828.7c6a2337@skybase> <20090624123416.GB9510@linux-sh.org> <20090624124542.GB32306@elte.hu> <20090624131440.GA9700@linux-sh.org> <20090624132447.GD6224@elte.hu> <1245999685.31755.157.camel@twins> <20090626072350.GI14078@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090626072350.GI14078@elte.hu> 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: 1286 Lines: 31 On Fri, Jun 26, 2009 at 09:23:50AM +0200, Ingo Molnar wrote: > > * Peter Zijlstra wrote: > > > On Wed, 2009-06-24 at 15:24 +0200, Ingo Molnar wrote: > > > > > > [ And long-term analysis ('perf stat' type of runs) dont need IRQs > > > anyway - perfcounters reads outs the counts and summarizes them > > > across the measured workload. ] > > > > If the counter width is less than 64 bits we do need to have some > > interrupt to read them from before they cycle so we can accumulate > > the deltas into a proper u64. > > Yeah - but even that can be driven from some housekeeping hrtimer. > > > But for proper 64 bit hardware counters there is indeed no need > > for that. > > Indeed - although they are rare. > We have both full 64-bit counters as well as 48-bit, although they do both at least set an overflow bit that can be looked at, even if there is no exception associated with it. Optionally they can be split up in to multiple 32-bit counters and half of them handed over to the bus controller. -- 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/