From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner+willy=40w.ods.org-S261332AbVFBX4B@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S261332AbVFBX4B (ORCPT <rfc822;willy@w.ods.org>);
	Thu, 2 Jun 2005 19:56:01 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261435AbVFBX4A
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Thu, 2 Jun 2005 19:56:00 -0400
Received: from rwcrmhc14.comcast.net ([216.148.227.89]:47871 "EHLO
	rwcrmhc14.comcast.net") by vger.kernel.org with ESMTP
	id S261332AbVFBXzx (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Thu, 2 Jun 2005 19:55:53 -0400
X-Comment: AT&T Maillennium special handling code - c
From: Parag Warudkar <kernel-stuff@comcast.net>
To: john stultz <johnstul@us.ibm.com>
Subject: Re: [PATCH 3/4] new timeofday x86-64 arch specific changes (v. B1)
Date: Thu, 2 Jun 2005 19:50:33 -0400
User-Agent: KMail/1.8
Cc: Nishanth Aravamudan <nacc@us.ibm.com>, Andi Kleen <ak@suse.de>,
       lkml <linux-kernel@vger.kernel.org>,
       Tim Schmielau <tim@physik3.uni-rostock.de>,
       George Anzinger <george@mvista.com>, albert@users.sourceforge.net,
       Ulrich Windl <ulrich.windl@rz.uni-regensburg.de>,
       Christoph Lameter <clameter@sgi.com>,
       Dominik Brodowski <linux@dominikbrodowski.de>,
       David Mosberger <davidm@hpl.hp.com>, Andrew Morton <akpm@osdl.org>,
       paulus@samba.org, schwidefsky@de.ibm.com,
       keith maanthey <kmannth@us.ibm.com>, Chris McDermott <lcm@us.ibm.com>,
       Max Asbock <masbock@us.ibm.com>, mahuja@us.ibm.com,
       Darren Hart <darren@dvhart.com>, "Darrick J. Wong" <djwong@us.ibm.com>,
       Anton Blanchard <anton@samba.org>, donf@us.ibm.com, mpm@selenic.com,
       benh@kernel.crashing.org
References: <060220051827.15835.429F4FA6000DF9D700003DDB220588617200009A9B9CD3040A029D0A05@comcast.net> <200506021905.08274.kernel-stuff@comcast.net> <1117754453.17804.51.camel@cog.beaverton.ibm.com>
In-Reply-To: <1117754453.17804.51.camel@cog.beaverton.ibm.com>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="utf-8"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200506021950.35014.kernel-stuff@comcast.net>
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org

On Thursday 02 June 2005 19:20, john stultz wrote:
> Could you see if the slowness you're feeling is correlated to the
> acpi_pm timesource?

Speaking of which, the below code from arch/i386/timer_pm.c looks particularly 
more taxing to me - 3 times read from ioport in a loop - not sure how many 
time that executes. 

static inline u32 read_pmtmr(void)
{
        u32 v1=0,v2=0,v3=0;
        /* It has been reported that because of various broken
         * chipsets (ICH4, PIIX4 and PIIX4E) where the ACPI PM time
         * source is not latched, so you must read it multiple
         * times to insure a safe value is read.
         */
        do {
                v1 = inl(pmtmr_ioport);
                v2 = inl(pmtmr_ioport);
                v3 = inl(pmtmr_ioport);
        } while ((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
                        || (v3 > v1 && v3 < v2));

Shouldn't that loop be limited to the broken chipsets - why would correct 
people with correctly working chipsets carry this extra burden? (Or is it 
insignificant?)

-- 
Because we don't think about future generations, they will never forget us.
		-- Henrik Tikkanen