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SubjectRe: [PATCH 2/3] x86, fpu: unlazy_fpu: don't do __thread_fpu_end() if use_eager_fpu()
On 01/29/2015 04:49 PM, Oleg Nesterov wrote:

> Yes. But in this case tsk != current, and we ensure that __switch_to()
> was finished. wait_task_inactive().
>
>> When we switch to the traced task, the __thread_fpu_end()
>> that was called from init_fpu() ensures that
>> switch_fpu_begin() will actually load the new FPU state
>> from memory into the registers, and we will not take
>> the fpu_lazy_restore() branch.
>
> No. in this case we rely on "tsk->thread.fpu.last_cpu = ~0" which disables
> fpu_lazy_restore().

I should have known that.

Especially considering I have a patch here that
converts "tsk->thread.fpu.last_cpu = ~0" into
a disable_lazy_restore() call...



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