Re: preempt timing violations (unmap_vmas)

[Rudo Thomas]

Hello.

> > 2ms non-preemptible critical section violated 1 ms preempt threshold
> > starting at unmap_vmas+0x1ff/0x210 and ending at
> > unmap_vmas+0x1f5/0x210
> 
> this is the normal sys_exit()->exit_mmap()->unmap_vmas() path. It's
> weird that it generated a 2ms latency. What are the values of
> voluntary_preemption and kernel_preemption on your current kernel? With
> a 2:0 setting we ought to have a reschedule point every 32 pages.  Do
> you know which application triggers this latency and is it easy to
> reproduce?

I discovered that I got two of these in a row. The settings are 2:1, but I am
not able to reproduce it.

Rudo.
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