From owner-dev-commits-src-all@freebsd.org Wed Sep 8 17:47:44 2021 Return-Path: Delivered-To: dev-commits-src-all@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 41D7B67EA47 for ; Wed, 8 Sep 2021 17:47:44 +0000 (UTC) (envelope-from cperciva@freebsd.org) Received: from mail.tarsnap.com (mail.tarsnap.com [54.86.246.204]) by mx1.freebsd.org (Postfix) with SMTP id 4H4V340wyMz4pfJ for ; Wed, 8 Sep 2021 17:47:44 +0000 (UTC) (envelope-from cperciva@freebsd.org) Received: (qmail 86914 invoked from network); 8 Sep 2021 17:47:38 -0000 Received: from unknown (HELO dell7390.daemonology.net) (127.0.0.1) by mail.tarsnap.com with SMTP; 8 Sep 2021 17:47:38 -0000 Received: (qmail 1150 invoked from network); 8 Sep 2021 17:47:38 -0000 Received: from unknown (HELO dell7390.daemonology.net) (127.0.0.1) by localhost with SMTP; 8 Sep 2021 17:47:38 -0000 To: John Baldwin , src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org References: <202109080132.1881WXPv069848@gitrepo.freebsd.org> From: Colin Percival Subject: Re: git: a8b89dff6ac0 - main - Disable acpi_timer_test by default Message-ID: <4b7bf983-8333-f4bc-6ce8-a59ac2fc7380@freebsd.org> Date: Wed, 8 Sep 2021 10:47:37 -0700 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 4H4V340wyMz4pfJ X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[] X-BeenThere: dev-commits-src-all@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for all branches of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 08 Sep 2021 17:47:44 -0000 On 9/8/21 9:01 AM, John Baldwin wrote: > On 9/7/21 6:32 PM, Colin Percival wrote: >>      Disable acpi_timer_test by default >>           This disables testing the ACPI timer by default, forcing the use of >>      ACPI-fast rather than ACPI-safe.  The broken-ACPI-timers workaround >>      can be re-enabled by setting the hw.acpi.timer_test_enabled=1 tunable. >>           This speeds up the FreeBSD boot process by 140 ms on an EC2 c5.xlarge >>      instance. >>           This change will not be MFCed. >>           Assuming no problems are reported, acpi_timer_test, the associated >>      tunable, and the ACPI-safe timecounter should be removed in FreeBSD 15. >>           Relnotes:       The ACPI-safe timer is disabled in favour of >> ACPI-fast; >>                      if timekeeping issues are observed, please test with >>                      hw.acpi.timer_test_enabled=1 in loader.conf and report >>                      if that fixes the problem. > > Perhaps it should default to '1' for i386 and '0' otherwise?  The relevant > chipsets were 32-bit only, so this would be a simple way to skip the test for > modern hardware, and you could probably MFC that safely. That option was discussed, but I decided that it was probably safer to keep it enabled by default in 13 in case the test was detecting systems which are broken in other ways. Googling for "ACPI-safe" (which shows up if the test fails) finds forum discussions from the mid-2010s, but it's not clear whether that's due to very old hardware, new ACPI timer issues, or other timekeeping problems -- I figured it was best to play it safe for something which would be going into a stable branch though. -- Colin Percival Security Officer Emeritus, FreeBSD | The power to serve Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid