• Matt Fleming's avatar
    perf tests: Add Intel CQM test · 035827e9
    Matt Fleming authored
    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().
    Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
    Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
    Cc: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Kanaka Juvva <kanaka.d.juvva@intel.com>
    Cc: Vikas Shivappa <vikas.shivappa@intel.com>
    Cc: Vince Weaver <vince@deater.net>
    Link: http://lkml.kernel.org/r/1437490509-15373-1-git-send-email-matt@codeblueprint.co.uk
    Link: http://lkml.kernel.org/n/tip-3p4ra0u8vzm7m289a1m799kf@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    035827e9
arch-tests.c 606 Bytes