stable-8 regression: time stands still
freebsd at jdc.parodius.com
Wed Mar 3 11:47:29 UTC 2010
On Wed, Mar 03, 2010 at 11:16:51AM +0000, Tom Evans wrote:
> On Wed, Mar 3, 2010 at 11:09 AM, Jeremy Chadwick
> <freebsd at jdc.parodius.com> wrote:
> > On Wed, Mar 03, 2010 at 09:09:56AM +0100, Ruben de Groot wrote:
> >> > > I'm going to get this kern.timecounter sysctl from the system booted with a 7.x livecd
> >> > > this evening. But really, I think this is a regression. Even if this system is the only
> >> > > one known to be affected (which I sincerely doubt).
> >> >
> >> > You can force a timecounter choice by setting it in /boot/loader.conf.
> >> > I would recommend choosing ACPI-safe on your system to see if that
> >> > improves things:
> >> >
> >> > kern.timecounter.hardware=ACPI-safe
> >> Thanks, that solved my issue. Allthough for correctness I must add that this line
> >> must be put in /etc/sysctl.conf; it does nothing in loader.conf.
> >> Also the sysctl can be run in multiuser and immediately fixed the problem.
> > Ah, I thought it was a loader tunable, not a sysctl tunable. My
> > apologies! Yes, sysctl.conf is the correct place for this.
> >> One question remains: why did this suddenly become a problem in FreeBSD 8 and not
> >> in FreeBSD 7.
> > That would be a question for the people who decided upon the timecounter
> > priorities in FreeBSD, since they're hard-coded (meaning: why HPET is
> > chosen above ACPI-safe). This may have changed between RELENG_7 and
> > RELENG_8; I simply don't know. It would be easy to verify on your
> > system of course (just boot a FreeBSD 7 LiveCD and provide the output
> > from sysctl kern.timecounter).
> Another possibility could be that RELENG_7 was finding ACPI-fast,
> which is rated above HPET. I'm not sure why some machines get
> ACPI-fast and some get ACPI-safe - I think ACPI-fast is tested at boot
> up, and if the measurements are not consistent, it disables ACPI-fast
> and uses ACPI-safe instead, which is then ignored when HPET is
I believe that question got answered last month:
| Jeremy Chadwick jdc at parodius.com |
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| UNIX Systems Administrator Mountain View, CA, USA |
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