From owner-freebsd-questions@FreeBSD.ORG Tue Nov 29 19:25:54 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E6119106564A for ; Tue, 29 Nov 2011 19:25:54 +0000 (UTC) (envelope-from amvandemore@gmail.com) Received: from mail-bw0-f54.google.com (mail-bw0-f54.google.com [209.85.214.54]) by mx1.freebsd.org (Postfix) with ESMTP id 709498FC0C for ; Tue, 29 Nov 2011 19:25:54 +0000 (UTC) Received: by bkbzs8 with SMTP id zs8so13105976bkb.13 for ; Tue, 29 Nov 2011 11:25:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=aORNRRN5/gYRAvBHIIAeCqe3hE18fERmFqO2mvxX/hA=; b=ihOZ3x/KfSYZbVUgRIM30yRKT3sAdwDdJhC7bapVVALxJpFtMl9j+Zcm8Rt58jBAt2 bDTiq4BRAaXj29WeMV11Oo2t5k7GLkt0cqd10mw7TsR+QHZS/5S9UcoYzkxaYi542rIk gehrp+7HdvvQZCOZqQggVUAHFPBsRWC2PTXRA= MIME-Version: 1.0 Received: by 10.204.10.81 with SMTP id o17mr51771862bko.65.1322594753262; Tue, 29 Nov 2011 11:25:53 -0800 (PST) Received: by 10.223.83.14 with HTTP; Tue, 29 Nov 2011 11:25:53 -0800 (PST) In-Reply-To: <4ED525B1.3010100@wp.pl> References: <4ED525B1.3010100@wp.pl> Date: Tue, 29 Nov 2011 13:25:53 -0600 Message-ID: From: Adam Vande More To: Ireneusz Pluta Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-questions@freebsd.org Subject: Re: kern.timecounter.hardware change on the fly X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 29 Nov 2011 19:25:55 -0000 On Tue, Nov 29, 2011 at 12:34 PM, Ireneusz Pluta wrote: > is it safe to change kern.timecounter.hardware on a busy production system > on the fly? Or I better schedule a downtime to do that? > > It seems I got a bad current selection, somehow, probably as an effect of > leaving /etc/sysctl.conf contents of early experimental setup stage of this > machine. > > $ sysctl -a | grep timecounter > kern.timecounter.tick: 1 > kern.timecounter.choice: TSC(-100) HPET(900) ACPI-fast(1000) i8254(0) > dummy(-1000000) > kern.timecounter.hardware: i8254 > kern.timecounter.stepwarnings: 0 > kern.timecounter.tc.i8254.**mask: 65535 > kern.timecounter.tc.i8254.**counter: 23813 > kern.timecounter.tc.i8254.**frequency: 1193182 > kern.timecounter.tc.i8254.**quality: 0 > kern.timecounter.tc.ACPI-fast.**mask: 16777215 > kern.timecounter.tc.ACPI-fast.**counter: 4619803 > kern.timecounter.tc.ACPI-fast.**frequency: 3579545 > kern.timecounter.tc.ACPI-fast.**quality: 1000 > kern.timecounter.tc.HPET.mask: 4294967295 > kern.timecounter.tc.HPET.**counter: 1703441786 > kern.timecounter.tc.HPET.**frequency: 14318180 > kern.timecounter.tc.HPET.**quality: 900 > kern.timecounter.tc.TSC.mask: 4294967295 > kern.timecounter.tc.TSC.**counter: 2720513805 > kern.timecounter.tc.TSC.**frequency: 2266656152 > kern.timecounter.tc.TSC.**quality: -100 > kern.timecounter.smp_tsc: 0 > kern.timecounter.invariant_**tsc: 1 > > This setting seems to affect what is generally described here: > http://archives.postgresql.**org/pgsql-admin/2011-01/**msg00059.phpand this is the primary reason I want to change. > > Should I switch to HPET or ACPI-fast? > I don't know of any reason it would be unsafe to switch. There have been conflicting reports vs the speed of HPET and ACPI-fast probably at least in part due to hardware differences. You should test each if performance is a concern for you. -- Adam Vande More