Re: [RFC PATCH v3 0/3] x86/perf/amd: AMD PMC counters and NMI latency

[Vince Weaver]

On Tue, 2 Apr 2019, Cyrill Gorcunov wrote:
> On Tue, Apr 02, 2019 at 03:03:02PM +0200, Peter Zijlstra wrote:
> > I have vague memories of the P4 thing crashing with Vince's perf_fuzzer,
> > but maybe I'm wrong.
> 
> No, you're correct. p4 was crashing many times before we manage to make
> it more-less stable. The main problem though that to find working p4 box
> is really a problem.

I do have some a functioning p4 system I can test on.
I can easily run the fuzzer and report crashes, but I only have limited 
time/skills to actually fix the problems it turns up.

One nice thing is that as of Linux 5.0 *finally* the fuzzer can run 
indefinitely on most modern Intel chips without crashing (still triggers a 
few warnings).  So finally we have the ability to tell when a new crash is 
a regression and potentially can bisect it.  Although obviously this 
doesn't necessarily apply to the p4.

I do think the number of people trying to run perf on a p4 is probably 
pretty small these days.

Vince