Thomas Gleixner wrote:
On Tue, 9 Oct 2007, John Sigler wrote:
I'm using a -rt kernel with high resolution timer support.
http://rt.wiki.kernel.org/index.php/Main_Page
Linux version 2.6.22.1-rt9 (root@venus) (gcc version 3.4.6) #1 PREEMPT RT Tue
Oct 9 10:02:45 CEST 2007
I enabled high resolution timer support and disabled ACPI support.
...
High resolution timers do not work in this configuration.
Correct
Any idea why?
Yes
# cat /sys/devices/system/clocksource/clocksource0/available_clocksource
tsc pit jiffies
# cat /sys/devices/system/clocksource/clocksource0/current_clocksource
tsc
My timestamp counter is good. Why do I need ACPI for hrt?
We do not trust TSC at all. Never ever.
The kernel refuses to switch to high resolution mode, when there is no
reliable backup clock source available. ACPI enables the acpi_pm
timer, which is a trusted clock source and is used by the kernel to
verify the correctness of the TSC. You might try to enable HPET.
OK. I seem to remember that you had a patch to enable HPET on ICH4?
Is it still available somewhere?
Regards.
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