From owner-freebsd-current Mon Apr 1 15:09:05 1996 Return-Path: owner-current Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id PAA10478 for current-outgoing; Mon, 1 Apr 1996 15:09:05 -0800 (PST) Received: from Root.COM (implode.Root.COM [198.145.90.17]) by freefall.freebsd.org (8.7.3/8.7.3) with ESMTP id PAA10473 for ; Mon, 1 Apr 1996 15:09:00 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by Root.COM (8.7.5/8.6.5) with SMTP id PAA10081; Mon, 1 Apr 1996 15:09:23 -0800 (PST) Message-Id: <199604012309.PAA10081@Root.COM> X-Authentication-Warning: implode.Root.COM: Host localhost [127.0.0.1] didn't use HELO protocol To: Bruce Evans cc: freebsd-current@freefall.freebsd.org, kuku@gilberto.physik.rwth-aachen.de Subject: Re: calcru: negative time: From: David Greenman Reply-To: davidg@Root.COM Date: Mon, 01 Apr 1996 15:09:22 -0800 Sender: owner-current@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk >>>[deleted] >>>calcru: negative time: -11929 usec >>>calcru: negative time: -3909 usec >>>calcru: negative time: -3842 usec >>>calcru: negative time: -17709 usec >>>calcru: negative time: -3480 usec >> >>This is caused by hardclock() interrupt latency. The problem is >>especially noticable on i586's and i686's because any latency causes the >>clock to go backwards; on i386's and i486's, the latency must be > 1 >>clock tick (10000 usec) to cause problems. Normally the latency on >>i586's is > 0 but < 10 usec and isn't detectable. There must be bugs >>elsewhere to cause latencies of more than a few tens of usecs. > > I'm not convinced that this is a latency problem. The problem has suddenly >gotten about 1000 times worse earlier today on both -current and -stable >simultaneously...and it's not due to any code changes or load changes. I saw >the problem on machines ranging from wcarchive to my X terminal (which is I'd like to also add that regardless of latency, there's only one word that can describe a clock going backwards: broken. This simply shouldn't happen, ever, and should be fixed. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project