Re: Loongson (and other $ARCHs?) idle VS timer enqueue

[Peter Zijlstra]

On Fri, Apr 21, 2023 at 06:47:29PM +0200, Frederic Weisbecker wrote:

> > *HOWEVER*
> > 
> > intel_idle_irq() is affected -- except that we only (normally) use that
> > for very shallow idle states and it won't interact with NOHZ (because we
> > only disable the tick for deep idle states).
> 
> Well I don't know, that doesn't look comfortable... :)
> 
> Also why does it need to enable IRQs if ecx=1 ?

Supposedly this is some interrupt latency hack. See commit:

  c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons")