Re: [PATCH] Re: x86_32 tsc/pit and hrtimers

From: Chris Snook
Date: Thu Oct 09 2008 - 14:40:35 EST


Thomas Gleixner wrote:
On Wed, 8 Oct 2008, Jeff Hansen wrote:

[HRTIMER]: Add highres=noverify option to bypass clocksource verification

This disregards the CLOCK_SOURCE_MUST_VERIFY flag on all clocksources.
This is particularly useful on legacy x86_32 systems that have no ACPI,
LAPIC, or HPET timers, where only TSC and PIT are available.

While I agree in principle, adding this to highres is the wrong thing
to do. This is a property of clocksources and not of high resolution
timer support.

The affected clocksource is TSC and it should go there as a command
line option e.g. tsc=stable, which in turn clears the
CLOCK_SOURCE_MUST_VERIFY flag in the tsc clocksource.

Thanks,

tglx

Fair enough, but do you think it's worthwhile to have an option to disable CLOCK_SOURCE_MUST_VERIFY checking for all timers, or should we implement this on a case-by-case basis when there's legitimate cause, like with TSC?

-- Chris
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/