2021-01-26 10:50:31

by Zhang, Qiang

Subject: Question on migrate_disabe/enable()

Hello Peterz, tglx

I have some questions about migrate_disabe/enable(), in the past migrate_disabe/enable() is replaced by preempt_disable/enable() in no RT system.

And now migrate_disabe/enable() has its own implementation, I want to know in migrate_disabe/enable() critical area is blocking allowed?

If allowed, There's a blockage in migrate_disabe/enable() critical area, and this time if CPU going offline??offline time will be longer. Is this normal phenomenon??

Thanks
Qiang

2021-01-26 20:40:07

by Peter Zijlstra

Subject: Re: Question on migrate_disabe/enable()

On Tue, Jan 26, 2021 at 02:12:45AM +0000, Zhang, Qiang wrote:
> Hello Peterz, tglx
>
> I have some questions about migrate_disabe/enable(), in the past
> migrate_disabe/enable() is replaced by preempt_disable/enable() in no
> RT system.
>
> And now migrate_disabe/enable() has its own implementation, I want to
> know in migrate_disabe/enable() critical area is blocking allowed?

Yes, obviously. Otherwise it would've been preempt_disable().

> If allowed, There's a blockage in migrate_disabe/enable() critical
> area, and this time if CPU going offline，offline time will be longer.
> Is this normal phenomenon？

Ofcourse.