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Date: Sat, 21 Sep 2013 08:55:37 +0200
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Subject: Re: [PATCH V2 0/6] perf: New conditional branch filter
From: Stephane Eranian <eranian@google.com>
To: Michael Ellerman <michael@ellerman.id.au>
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Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>,
 LKML <linux-kernel@vger.kernel.org>,
 Arnaldo Carvalho de Melo <acme@redhat.com>,
 Linux PPC dev <linuxppc-dev@ozlabs.org>,
 Michael Neuling <michael.neuling@au1.ibm.com>,
 Anshuman Khandual <khandual@linux.vnet.ibm.com>
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On Tue, Sep 10, 2013 at 4:06 AM, Michael Ellerman
<michael@ellerman.id.au> 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?
>
The semantic on the API is OR. AND does not make sense: CALL & RETURN?
On x86, the HW filter is an OR (default: ALL, set bit to disable a
type). I suspect
it is similar on PPC.

>
> cheers
>
>