On 09-Feb-22 6:21 PM, Peter Zijlstra wrote: > On Thu, Feb 03, 2022 at 03:28:41PM +0530, Ravi Bangoria wrote: >> Perf counter may overcount for a list of Retire Based Events. Implement >> workaround for Zen3 Family 19 Model 00-0F processors as suggested in >> Revision Guide[1]: >> >> To count the non-FP affected PMC events correctly: >> o Use Core::X86::Msr::PERF_CTL2 to count the events, and >> o Program Core::X86::Msr::PERF_CTL2[43] to 1b, and >> o Program Core::X86::Msr::PERF_CTL2[20] to 0b. >> >> Note that the specified workaround applies only to counting events and >> not to sampling events. Thus sampling event will continue functioning >> as is. >> >> Although the issue exists on all previous Zen revisions, the workaround >> is different and thus not included in this patch. >> >> This patch needs Like's patch[2] to make it work on kvm guest. >> >> [1] https://bugzilla.kernel.org/attachment.cgi?id=298241 >> [2] https://lore.kernel.org/lkml/20220117055703.52020-1-likexu@xxxxxxxxxxx >> >> Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxx> > > Thanks! Peter, On subsequent tests, I found that this 'fix' is still not optimal. Please drop this patch from your queue for now. Really sorry for the noise. Thanks, Ravi
