Re: [PATCH RT 4/5] allow preemption in mem_cgroup_move_account_page_stat

[Nicholas Mc Guire]

On Fri, 14 Feb 2014, Sebastian Andrzej Siewior wrote:

> * Sebastian Andrzej Siewior | 2014-02-14 14:17:05 [+0100]:
> 
> >Now, that I look at it again. Isn't it more efficient to keep preemption
> >disabled for this very short time instead instead of invoking
> >migrate_disable() which includes preempt_disable()/enable() and a few
> >more opcodes???
> >Therefore, I drop it again.
> 
> I think doing the same for the 1/5 of this series since it also disables
> migration for a handfull of asm opcodes.
>
yup - nice run in the wrong direction :)
those short pushdowns make no sense - should have looked at that first...
the execution length/complexity (notably worst case on migrate_enable()) is
actually very high compared to a preempt_enable.

thx!
hofrat
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