On Wed, May 25, 2011 at 9:15 AM, Andriy Gapon <a...@freebsd.org> wrote:
> on 23/05/2011 19:28 Andriy Gapon said the following:
>> I propose the following path for moving forward.
>> - use hint.lapic.X.disabled to disable individual CPUs by their APIC ID
>> - use machdep.hyperthreading_allowed tunable to disable second logical CPU
>> on each
>> real core
>>
>> The above should already work as expected. One thing is that currently we
>> have
>> handling of machdep.hyperthreading_allowed tunable under SCHED_ULE. I plan
>> to
>> make it unconditional.
>>
>> Things to remove:
>> - all the related sysctls for dynamic onlining/offlining
>> - machdep.hlt_logical_cpus tunable (it duplicates hint.lapic.X.disabled)
>>
>> It's possible to keep machdep.hlt_logical_cpus and just add some code to
>> convert
>> hlt_logical_cpus mask to a set of individual hint.lapic.X.disabled, but I
>> don't
>> see very much value in that. But if there is a good reason to keep that
>> tunable,
>> I am prepared to jump through this hoop.
>>
>> If no one objects to this proposal, I will provide a patch soon.
>
> The patch is here:
> http://people.freebsd.org/~avg/cpu-offline-sysctl.diff
> It should implement the strategy described above.
>
> I have mp_watchdog alone for now. It seems to have the same issues with
> respect
> to dynamic CPU state change. Besides its compilation is disabled when
> SCHED_ULE
> is enabled. mp_watchdog is a nice idea, but I wonder if anyone actually uses
> it
> (with success).
I'll have to test out the patch, but at first glance it seems ok
(at least the machdep.hyperthreading_allowed changes which $WORK
depends upon).
Thanks!
-Garrett
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