From owner-freebsd-performance@FreeBSD.ORG Thu Apr 30 21:52:52 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 0E2E3106564A; Thu, 30 Apr 2009 21:52:52 +0000 (UTC) (envelope-from bruce@cran.org.uk) Received: from muon.cran.org.uk (brucec-1-pt.tunnel.tserv4.nyc4.ipv6.he.net [IPv6:2001:470:1f06:c09::2]) by mx1.freebsd.org (Postfix) with ESMTP id BBF3B8FC28; Thu, 30 Apr 2009 21:52:51 +0000 (UTC) (envelope-from bruce@cran.org.uk) Received: from muon.cran.org.uk (localhost [127.0.0.1]) by muon.cran.org.uk (Postfix) with ESMTP id 9B2B11900F; Thu, 30 Apr 2009 22:52:54 +0000 (GMT) X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on muon X-Spam-Level: X-Spam-Status: No, score=-2.6 required=8.0 tests=AWL,BAYES_00,NO_RELAYS autolearn=ham version=3.2.5 Received: from gluon.draftnet (unknown [IPv6:2a01:348:10f:0:240:f4ff:fe57:9871]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by muon.cran.org.uk (Postfix) with ESMTPSA; Thu, 30 Apr 2009 22:52:54 +0000 (GMT) Date: Thu, 30 Apr 2009 22:52:45 +0100 From: Bruce Cran To: John Baldwin Message-ID: <20090430225245.538d073e@gluon.draftnet> In-Reply-To: <200904300846.41576.jhb@freebsd.org> References: <200904270150.31912.pieter@degoeje.nl> <7d6fde3d0904261927s1a67cf85jc982c1a68e30e081@mail.gmail.com> <200904300846.41576.jhb@freebsd.org> X-Mailer: Claws Mail 3.7.1 (GTK+ 2.14.7; i386-portbld-freebsd7.2) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Mailman-Approved-At: Thu, 30 Apr 2009 22:28:19 +0000 Cc: freebsd-hackers@freebsd.org, Pieter, freebsd-acpi@freebsd.org, 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: Thu, 30 Apr 2009 21:52:52 -0000 On Thu, 30 Apr 2009 08:46:41 -0400 John Baldwin wrote: > On Sunday 26 April 2009 10:27:42 pm Garrett Cooper wrote: > > 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". > http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/dev/acpica/acpi_hpet.c shows some of the history behind the decision. Apparently it used to be slower but it was hoped it would get faster as systems supported it better. I guess that's happening now. -- Bruce Cran