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Date: Wed, 22 Jul 2015 15:24:44 +0200 From: Jiri Olsa <jolsa@...hat.com> To: Matt Fleming <matt@...eblueprint.co.uk> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>, linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>, Andi Kleen <andi@...stfloor.org>, Vince Weaver <vince@...ter.net>, Matt Fleming <matt.fleming@...el.com>, Peter Zijlstra <peterz@...radead.org> Subject: Re: [RFC][PATCH] perf tests: Add Intel CQM and arch tests On Wed, Jul 22, 2015 at 11:38:59AM +0100, Matt Fleming wrote: > From: Matt Fleming <matt.fleming@...el.com> > > Peter reports that it's possible to trigger a WARN_ON_ONCE() in the > Intel CQM code by combining a hardware event and an Intel CQM (software) > event into a group. Unfortunately, the perf tools are not able to create > this bundle and we need to manually construct a test case. > > For posterity, record Peter's proof of concept test case in tools/perf > so that it presents a model for how we can perform architecture-specific > tests, or "arch tests", in perf in the future. > > The particular issue triggered in the test case is that when the counter > for the hardware event overflows and triggers a PMI we'll read both the > hardware event and the software event counters. Unfortunately, for CQM > that involves performing an IPI to read the CQM event counters on all > sockets, which in NMI context triggers the WARN_ON_ONCE(). > > This patch is marked as RFC because I'd really like to solicit opinions > on this approach and hear feedback on whether this is the correct way to > structure these arch tests. I realise that we've already got tests for > the TSC, etc that are x86-specific but I didn't want to change the order > of the tests (say, by moving test__perf_time_to_tsc() into ARCH_TESTS) > in case that broke some kind of ABI. I wouldn't consider the order of tests being ABI, let's break it and watch ;-) SNIP > diff --git a/tools/perf/arch/x86/include/arch-tests.h b/tools/perf/arch/x86/include/arch-tests.h > new file mode 100644 > index 000000000000..9d43f759e014 > --- /dev/null > +++ b/tools/perf/arch/x86/include/arch-tests.h > @@ -0,0 +1,13 @@ > +#ifndef ARCH_TESTS_H > +#define ARCH_TESTS_H > + > +/* Tests */ > +int test__intel_cqm_count_nmi_context(void); > + > +#define ARCH_TESTS \ > + { \ > + .desc = "Test intel cqm nmi context read", \ > + .func = test__intel_cqm_count_nmi_context, \ > + }, > + hum, I dont like much this being stuffed in macro, but dont have any technical reason against ;-) maybe we could add 'struct test arch_tests[]' array, that'd be initialized by each arch and executed in addition to the current 'struct test tests[]' jirka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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