lkml.org 
[lkml]   [2017]   [May]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter
> > You would only need a single one per system however, not one per CPU.
> > RCU already tracks all the CPUs, all we need is a single NMI watchdog
> > that makes sure RCU itself does not get stuck.
> >
> > So we just have to find a single watchdog somewhere that can trigger
> > NMI.
>
> But then you have to IPI broadcast the NMI, which is less than ideal.

Only when the watchdog times out to print the backtraces.

>
> RCU doesn't have that problem because the quiescent state is a global
> thing. CPU progress, which is what the NMI watchdog tests, is very much
> per logical CPU though.

RCU already has a CPU stall detector. It should work (and usually
triggers before the NMI watchdog in my experience unless the
whole system is dead)

-Andi

\
 
 \ /
  Last update: 2017-05-30 19:23    [W:0.135 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site