From owner-freebsd-stable@FreeBSD.ORG Wed Mar 3 11:17:04 2010 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id AEB47106564A for ; Wed, 3 Mar 2010 11:17:04 +0000 (UTC) (envelope-from tevans.uk@googlemail.com) Received: from mail-ew0-f226.google.com (mail-ew0-f226.google.com [209.85.219.226]) by mx1.freebsd.org (Postfix) with ESMTP id 3DEEA8FC0C for ; Wed, 3 Mar 2010 11:17:03 +0000 (UTC) Received: by ewy26 with SMTP id 26so828541ewy.3 for ; Wed, 03 Mar 2010 03:16:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=9rZ/wI6brPDEZ4vp8zm/xGLBITUZiFd/wvLQ02x5PoA=; b=Z8/Fa6dbLpC52U9nFcXVf2EG2Bc27fg+/GZVzYONBayJouJn35qTH+dgUhvpvqVriU raBWPjwViTZt0cZkQUGLJP713lW25IgsPROsHojyga5TDE6Yf/VOCHoUcK1gUeu1qmds Xc8CkmRK3NF1zKtw4Wp34HJiK8piYA7YbbebE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=AYqQ9qFOrYzkPj4W0ywY3ymEWJLxSIDZLYhoO15qpt3flRJE/mb/6LbneQpJ7ONKsS x+W5aKB8Oe2KlWXEYxRAG7bDGirAHeMrYXHAyBQJEMpxsCNzO4dAYYYuxCkeQioWTnE4 +1CPG1ucxF/VuEOJPMeGIAEYzYQz+kzwvv8Xc= MIME-Version: 1.0 Received: by 10.213.53.71 with SMTP id l7mr2056816ebg.10.1267615011546; Wed, 03 Mar 2010 03:16:51 -0800 (PST) In-Reply-To: <20100303110901.GB51588@icarus.home.lan> References: <20100301203450.GA99170@ei.bzerk.org> <20100301211441.GB99170@ei.bzerk.org> <20100302084347.GA4719@ei.bzerk.org> <20100302171227.GA26933@ei.bzerk.org> <20100302173632.GA29314@icarus.home.lan> <20100303080956.GA32493@ei.bzerk.org> <20100303110901.GB51588@icarus.home.lan> Date: Wed, 3 Mar 2010 11:16:51 +0000 Message-ID: <2e027be01003030316v719ae418o35ec64ab33aae9df@mail.gmail.com> From: Tom Evans To: Jeremy Chadwick Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: freebsd-stable@freebsd.org, Ruben de Groot , "C. P. Ghost" Subject: Re: stable-8 regression: time stands still X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Mar 2010 11:17:04 -0000 On Wed, Mar 3, 2010 at 11:09 AM, Jeremy Chadwick wrote: > On Wed, Mar 03, 2010 at 09:09:56AM +0100, Ruben de Groot wrote: >> > > I'm going to get this kern.timecounter sysctl from the system booted= with a 7.x livecd >> > > this evening. But really, I think this is a regression. Even if this= system is the only >> > > one known to be affected (which I sincerely doubt). >> > >> > You can force a timecounter choice by setting it in /boot/loader.conf. >> > I would recommend choosing ACPI-safe on your system to see if that >> > improves things: >> > >> > kern.timecounter.hardware=3DACPI-safe >> >> Thanks, that solved my issue. Allthough for correctness I must add that = this line >> must be put in /etc/sysctl.conf; it does nothing in loader.conf. >> Also the sysctl can be run in multiuser and immediately fixed the proble= m. > > Ah, I thought it was a loader tunable, not a sysctl tunable. =C2=A0My > apologies! =C2=A0Yes, sysctl.conf is the correct place for this. > >> One question remains: why did this suddenly become a problem in FreeBSD = 8 and not >> in FreeBSD 7. > > That would be a question for the people who decided upon the timecounter > priorities in FreeBSD, since they're hard-coded (meaning: why HPET is > chosen above ACPI-safe). =C2=A0This may have changed between RELENG_7 and > RELENG_8; I simply don't know. =C2=A0It would be easy to verify on your > system of course (just boot a FreeBSD 7 LiveCD and provide the output > from sysctl kern.timecounter). > Another possibility could be that RELENG_7 was finding ACPI-fast, which is rated above HPET. I'm not sure why some machines get ACPI-fast and some get ACPI-safe - I think ACPI-fast is tested at boot up, and if the measurements are not consistent, it disables ACPI-fast and uses ACPI-safe instead, which is then ignored when HPET is available. Cheers Tom