Messages in this thread | | | Date | Tue, 10 Sep 2013 09:22:51 +0530 | From | Anshuman Khandual <> | Subject | Re: [PATCH V2 0/6] perf: New conditional branch filter |
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On 09/10/2013 07:36 AM, Michael Ellerman wrote: > On Fri, 2013-08-30 at 09:54 +0530, Anshuman Khandual wrote: >> This patchset is the re-spin of the original branch stack sampling >> patchset which introduced new PERF_SAMPLE_BRANCH_COND filter. This patchset >> also enables SW based branch filtering support for PPC64 platforms which have >> branch stack sampling support. With this new enablement, the branch filter support >> for PPC64 platforms have been extended to include all these combinations discussed >> below with a sample test application program. > > ... > >> Mixed filters >> ------------- >> (6) perf record -e branch-misses:u -j any_call,any_ret ./cprog >> Error: >> The perf.data file has no samples! >> >> NOTE: As expected. The HW filters all the branches which are calls and SW tries to find return >> branches in that given set. Both the filters are mutually exclussive, so obviously no samples >> found in the end profile. > > The semantics of multiple filters is not clear to me. It could be an OR, > or an AND. You have implemented AND, does that match existing behaviour > on x86 for example?
I believe it does match. X86 code drops the branch records (originally captured in the LBR) while applying the SW filters.
Regards Anshuman
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