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SubjectRe: [PATCH V4 0/5] powerpc, perf: BHRB based branch stack enablement on POWER8
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Anshuman,

IIRC there are new bits in the FSCR and HFSCR you need to enable for the
PMU and BRHB. Can you please check these are enabled?

Mikey

Anshuman Khandual <khandual@linux.vnet.ibm.com> wrote:
> Branch History Rolling Buffer (BHRB) is a new PMU feaure in IBM
> POWER8 processor which records the branch instructions inside the execution
> pipeline. This patchset enables the basic functionality of the feature through
> generic perf branch stack sampling framework.
>
> Sample output
> -------------
> $./perf record -b top
> $./perf report
>
> Overhead Command Source Shared Object Source Symbol Target Shared Object Target Symbol
> # ........ ....... .................... ...................................... .................... ...................................
> #
>
> 7.82% top libc-2.11.2.so [k] _IO_vfscanf libc-2.11.2.so [k] _IO_vfscanf
> 6.17% top libc-2.11.2.so [k] _IO_vfscanf [unknown] [k] 00000000
> 2.37% top [unknown] [k] 0xf7aafb30 [unknown] [k] 00000000
> 1.80% top [unknown] [k] 0x0fe07978 libc-2.11.2.so [k] _IO_vfscanf
> 1.60% top libc-2.11.2.so [k] _IO_vfscanf [kernel.kallsyms] [k] .do_task_stat
> 1.20% top [kernel.kallsyms] [k] .do_task_stat [kernel.kallsyms] [k] .do_task_stat
> 1.02% top libc-2.11.2.so [k] vfprintf libc-2.11.2.so [k] vfprintf
> 0.92% top top [k] _init [unknown] [k] 0x0fe037f4
>
> Changes in V2
> --------------
> - Added copyright messages to the newly created files
> - Modified couple of commit messages
>
> Changes in V3
> -------------
> - Incorporated review comments from Segher https://lkml.org/lkml/2013/4/16/350
> - Worked on a solution for review comment from Michael Ellerman https://lkml.org/lkml/2013/4/17/548
> - Could not move updated cpu_hw_events structure from core-book3s.c file into perf_event_server.h
> Because perf_event_server.h is pulled in first inside linux/perf_event.h before the definition of
> perf_branch_entry structure. Thats the reason why perf_branch_entry definition is not available
> inside perf_event_server.h where we define the array inside cpu_hw_events structure.
>
> - Finally have pulled in the code from perf_event_bhrb.c into core-book3s.c
>
> - Improved documentation for the patchset
>
> Changes in V4
> -------------
> - Incorporated review comments on V3 regarding new instruction encoding
>
> Anshuman Khandual (5):
> powerpc, perf: Add new BHRB related instructions for POWER8
> powerpc, perf: Add basic assembly code to read BHRB entries on POWER8
> powerpc, perf: Add new BHRB related generic functions, data and flags
> powerpc, perf: Define BHRB generic functions, data and flags for POWER8
> powerpc, perf: Enable branch stack sampling framework
>
> arch/powerpc/include/asm/perf_event_server.h | 7 ++
> arch/powerpc/include/asm/ppc-opcode.h | 8 ++
> arch/powerpc/perf/Makefile | 2 +-
> arch/powerpc/perf/bhrb.S | 44 +++++++
> arch/powerpc/perf/core-book3s.c | 167 ++++++++++++++++++++++++++-
> arch/powerpc/perf/power8-pmu.c | 57 ++++++++-
> 6 files changed, 280 insertions(+), 5 deletions(-)
> create mode 100644 arch/powerpc/perf/bhrb.S
>
> --
> 1.7.11.7
>


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