On Tue, Apr 02, 2019 at 10:53:38AM -0400, Vince Weaver wrote: > 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.
You know, running fuzzer on p4 might worth in anycase. As to potential problems to fix -- i could try find some time slot for, still quite limited too 'cause of many other duties :( > 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. Quite agree. Moreover current p4 perf code doesn't cover all potential functionality (for example cascaded counters) and nobody ever complained about it, I think exactly because not that many p4 boxes left and putting efforts into this perf module development doesn't look like a good investment, better to stick with more modern cpus and deprecate p4 with small steps.