Re: [PATCH] stop_machine: disable preempt in stop machine path

[Andrew Morton]

On Wed, 16 Sep 2009 15:26:54 +0800
Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx> wrote:

> We can disable preempt in stop_cpu(), It can reduce the cpu's waiting time
> and make stop_machine path faster.
> 

"it can"?  But does it?  Are there any measurements or observations to
back this up?

The kstop threads are already created with create_rt_workqueue() (which
has super-secret undocumented semantics which I have cleverly
discovered mean "use SCHED_FIFO").

So we won't be getting preempted here anyway?
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