From owner-freebsd-current Fri Sep 8 12:43: 4 2000 Delivered-To: freebsd-current@freebsd.org Received: from critter.freebsd.dk (flutter.freebsd.dk [212.242.40.147]) by hub.freebsd.org (Postfix) with ESMTP id 1FF3C37B423; Fri, 8 Sep 2000 12:43:01 -0700 (PDT) Received: from critter (localhost [127.0.0.1]) by critter.freebsd.dk (8.11.0/8.9.3) with ESMTP id e88JgrN82051; Fri, 8 Sep 2000 21:42:53 +0200 (CEST) (envelope-from phk@critter.freebsd.dk) To: Mike Smith Cc: Greg Lehey , Kenneth Wayne Culver , John Baldwin , Steve Ames , freebsd-current@FreeBSD.ORG Subject: Re: microuptime() went backwards In-Reply-To: Your message of "Thu, 07 Sep 2000 22:43:11 PDT." <200009080543.WAA01815@mass.osd.bsdi.com> Date: Fri, 08 Sep 2000 21:42:53 +0200 Message-ID: <82049.968442173@critter> From: Poul-Henning Kamp Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG In message <200009080543.WAA01815@mass.osd.bsdi.com>, Mike Smith writes: >> > Sep 7 14:35:55 laptop /kernel: microuptime() went backwards (10412.355980 -> 10412, -694583121)y >> > >> > this is bad.. right ? :-) >> >> Well, at any rate it looks very funny. If this is a laptop, try >> building a kernel without apm and see if that helps. > >It only helps "hide" the problem. There's either *extremely* bogus data >coming in, or an arithmetic or sequencing error that's allowing a corrupt >timecounter to be seen. > >It might help to see the negative number as hex... I have collected all the emails I've received and I have identified at least two different causes: There is a bogus i8254 implementation on certain Athlon Mobos, this is a non-brainer since they should not use the i8254 but the TSC. There are negative numbers coming in from both the i8254 and in a few cases from the TSC. NTIMECOUNTER may be too low for certain systems, I'm still waiting for some feedback on that. Either way, I have a patch which I need to burn in in my lab, but right now I have a hard time getting my SMP box to even print out "Copyright..." when it boots :-( -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD coreteam member | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message