Date: Fri, 15 Sep 2000 02:02:03 -0700 (PDT) From: Jaye Mathisen <mrcpu@internetcds.com> To: Poul-Henning Kamp <phk@FreeBSD.ORG> Cc: current@FreeBSD.ORG, hackers@FreeBSD.ORG Subject: Re: looking for "microuptime went backwards" victims... Message-ID: <Pine.BSF.4.21.0009150200310.290-100000@apocalypse.cdsnet.net> In-Reply-To: <53059.968085674@critter>
next in thread | previous in thread | raw e-mail | index | archive | help
I get it on my newsserver pretty much every night when expire runs.
12 IDE drives on 3 Promise controllers.
I was just actually about to replace the MB, thinking it was just
something freaky or unstable.
I will try the patch.
On Mon, 4 Sep 2000, Poul-Henning Kamp wrote:
>
> I'm looking for the remaining victims of the dreaded "microuptime
> went backwards" message.
>
> If you can reliably reproduce the problem, please contact me, so
> we can arrange for some very detailed tracing to try to find out
> what exactly is going on. I have not been able to trigger the
> problem in my lab in a long time.
>
> If you see the message only occationally, please try the attached
> patch and let me know if this changes the picture. The patch is
> not meant as a fix, but it might reduce the impact of this condition
> considerably when it happens. Basically by reducing the width of
> the timecounter the magnitude of the hit we take if the timecounter
> goes backwards is reduced from about an hour to approx 110msec.
>
> Reducing the width to less than 17 bits starts to run the risk of
> ambiguity due to clock rollover.
>
> This patch may not be safe with PCAUDIO.
>
> Poul-Henning
>
> Index: clock.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/i386/isa/clock.c,v
> retrieving revision 1.155
> diff -u -r1.155 clock.c
> --- clock.c 2000/07/30 21:05:22 1.155
> +++ clock.c 2000/09/04 16:34:16
> @@ -194,7 +194,7 @@
> static struct timecounter i8254_timecounter = {
> i8254_get_timecount, /* get_timecount */
> 0, /* no poll_pps */
> - ~0u, /* counter_mask */
> + 0x1ffff, /* counter_mask */
> 0, /* frequency */
> "i8254" /* name */
> };
>
> --
> 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
>
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.4.21.0009150200310.290-100000>