On Wed, Mar 3, 2010 at 11:09 AM, Jeremy Chadwick <free...@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 available. Cheers Tom _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
