From owner-svn-src-head@freebsd.org Mon Oct 30 02:22:44 2017 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E3684E51FE5 for ; Mon, 30 Oct 2017 02:22:44 +0000 (UTC) (envelope-from ian@freebsd.org) Received: from pmta2.delivery6.ore.mailhop.org (pmta2.delivery6.ore.mailhop.org [54.200.129.228]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id BD5336F658 for ; Mon, 30 Oct 2017 02:22:44 +0000 (UTC) (envelope-from ian@freebsd.org) X-MHO-User: 1491f6d5-bd19-11e7-b50b-53dc5ecda239 X-Report-Abuse-To: https://support.duocircle.com/support/solutions/articles/5000540958-duocircle-standard-smtp-abuse-information X-Originating-IP: 73.78.92.27 X-Mail-Handler: DuoCircle Outbound SMTP Received: from ilsoft.org (unknown [73.78.92.27]) by outbound2.ore.mailhop.org (Halon) with ESMTPSA id 1491f6d5-bd19-11e7-b50b-53dc5ecda239; Mon, 30 Oct 2017 02:21:48 +0000 (UTC) Received: from rev (rev [172.22.42.240]) by ilsoft.org (8.15.2/8.15.2) with ESMTP id v9U2Mfep002595; Sun, 29 Oct 2017 20:22:41 -0600 (MDT) (envelope-from ian@freebsd.org) Message-ID: <1509330161.21609.86.camel@freebsd.org> Subject: Re: svn commit: r325108 - head/sys/amd64/vmm/io From: Ian Lepore To: Peter Grehan , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Date: Sun, 29 Oct 2017 20:22:41 -0600 In-Reply-To: <3b1ffc68-def3-04f6-2a1e-af44d6f3b4a5@freebsd.org> References: <201710292050.v9TKo3j5058456@repo.freebsd.org> <1509310495.21609.60.camel@freebsd.org> <3b1ffc68-def3-04f6-2a1e-af44d6f3b4a5@freebsd.org> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.18.5.1 FreeBSD GNOME Team Port Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Oct 2017 02:22:45 -0000 On Sun, 2017-10-29 at 15:15 -0700, Peter Grehan wrote: > > > > > > > >    Improve the performance of the hpet timer in bhyve guests by making the > > >    timer frequency a power of two.  This changes the frequency from 10 to > > >    16.7 MHz (2 ^ 24 HZ).  Using a power of two avoids roundoff errors when > > >    doing arithmetic in sbintime_t units. > > >     > > >    Testing shows this can fix erratic ntpd behavior in guests using the > > >    hpet timer (which is the default for multicore guests). > > >     > > >    Reported by: bsam@ > > > > > > Modified: > > >    head/sys/amd64/vmm/io/vhpet.c >   In the future please respect MAINTAINERS and file a phab review for  > code in this area. > > later, > > Peter. > > In fact I did check maintainers, and I just now checked it again, and seeing nothing on-point, wrote a really snarky reply. Luckily, before hitting send I realized you wouldn't have said anything unless there was an entry in there, so I checked like 4 more times before I noticed the line that begins vmm(4).  I had been looking for a line that began with sys/amd64. So... sorry about that.  Should I revert it and open a review? Longer-term, I was hoping to find some time over the next few weeks to further explore the roundoff errors in the timers and attempt a better fix, and I was definitely intending to put that up for review (especially because it involves math, and I'm always better off asking for help with that). -- Ian