Hi all,
Thanks to all of you answering to my post.
On 7.11.2007, Andrew Morton wrote:
> Ow. Yes, from my reading delay_tsc() can return early (or after
> heat-death-of-the-universe) if the TSCs are offset and if preemption
> migrates the calling task between CPUs.
>
> I suppose a lameo fix would be to disable preemption in delay_tsc().
I have seen the problem in delay_tsc(), but I was pusled by these lines
in my dmesg:
> Time: acpi_pm clocksource has been installed.
> Switched to high resolution mode on CPU 0
> Switched to high resolution mode on CPU 1
I thought (sort of) acpi_pm (but not tsc) is used in udelay().
The same delay_tsc() is used in both arches: i386 & x86_64
(and as I see from the proposed patches in -mm, also for
the new x86 arch). Should the patch be applied for all of them?
Quite similar function ia64_itc_udelay() is used in IA64, but one
find a coment before it:
/*
* Generic udelay assumes that if preemption is allowed and the thread
* migrates to another CPU, that the ITC values are synchronized across
* all CPUs.
*/
Are they really synchronized or similar patch: preempt_disable/enable()
should be applied?
What about all other arches?
Thanks.
Marin Mitov
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