From owner-freebsd-performance@FreeBSD.ORG Sun Jun 14 12:39:39 2009 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E5DE11065673; Sun, 14 Jun 2009 12:39:39 +0000 (UTC) (envelope-from kris@FreeBSD.org) Received: from kennaway-macbookpro.config (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id 37A1B8FC1C; Sun, 14 Jun 2009 12:39:38 +0000 (UTC) (envelope-from kris@FreeBSD.org) Message-ID: <4A34EF89.10107@FreeBSD.org> Date: Sun, 14 Jun 2009 13:39:37 +0100 From: Kris Kennaway User-Agent: Thunderbird 2.0.0.21 (Macintosh/20090302) MIME-Version: 1.0 To: John Baldwin References: <200904270150.31912.pieter@degoeje.nl> <7d6fde3d0904261927s1a67cf85jc982c1a68e30e081@mail.gmail.com> <200904300846.41576.jhb@freebsd.org> In-Reply-To: <200904300846.41576.jhb@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: acpi , freebsd-hackers@freebsd.org, freebsd-acpi@freebsd.org, Pieter de Goeje , Garrett Cooper , freebsd-performance@freebsd.org Subject: Re: ACPI-fast default timecounter, but HPET 83% faster X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 14 Jun 2009 12:39:40 -0000 John Baldwin wrote: > On Sunday 26 April 2009 10:27:42 pm Garrett Cooper wrote: >> I'm seeing similar results. >> >> [root@orangebox /usr/home/gcooper]# dmesg | grep 'Timecounter "' >> Timecounter "i8254" frequency 1193182 Hz quality 0 >> Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000 >> Timecounter "HPET" frequency 14318180 Hz quality 900 >> [root@orangebox /usr/home/gcooper]# ./cgt >> 1369355 >> [root@orangebox /usr/home/gcooper]# sysctl >> kern.timecounter.hardware="ACPI-fast" >> kern.timecounter.hardware: HPET -> ACPI-fast >> [root@orangebox /usr/home/gcooper]# ./cgt >> 772289 >> >> Why's the default ACPI-fast? For power-saving functionality or because >> of the `quality' factor? What is the criteria that determines the >> `quality' of a clock as what's being reported above (I know what >> determines the quality of a clock visually from a oscilloscope =])? > > I suspect that the quality of the HPET driver is lower simply because no one > had measured it previously and HPET is newer and less "proven". > From memory, HPET was massively slower on some of the AMD test hardware I was using. There was a thread about it on one of the mailing lists, but I can't find it right now. Kris