Re: [PATCH 2/3] x86, fpu: unlazy_fpu: don't do __thread_fpu_end() if use_eager_fpu()

[Rik van Riel]

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...

--
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/