[RFC 0/4] Add perf interface to expose nvdimm performance stats

[Kajol Jain]

Patchset adds performance stats reporting support for nvdimm.
Added interface includes support for a pmu register function and
callbacks to be used by arch/platform specific drivers.
User could use standard perf tool to access perf events exposed via pmu.

Patchset adds a structure called nvdimm_pmu which can
be used to add platform specific data like supported event list and
callbacks to pmu functions like event_init/add/delete/read.

Patchset includes an implements the to expose IBM pseries platform nmem*
device performance stats using this interface.

Result from power9 pseries lpar with 2 nvdimm device:
command:# perf list nmem
  nmem0/cchrhcnt/                                    [Kernel PMU event]
  nmem0/cchwhcnt/                                    [Kernel PMU event]
  nmem0/critrscu/                                    [Kernel PMU event]
  nmem0/ctlresct/                                    [Kernel PMU event]
  nmem0/ctlrestm/                                    [Kernel PMU event]
  nmem0/fastwcnt/                                    [Kernel PMU event]
  nmem0/hostlcnt/                                    [Kernel PMU event]
  nmem0/hostldur/                                    [Kernel PMU event]
  nmem0/hostscnt/                                    [Kernel PMU event]
  nmem0/hostsdur/                                    [Kernel PMU event]
  nmem0/medrcnt/                                     [Kernel PMU event]
  nmem0/medrdur/                                     [Kernel PMU event]
  nmem0/medwcnt/                                     [Kernel PMU event]
  nmem0/medwdur/                                     [Kernel PMU event]
  nmem0/memlife/                                     [Kernel PMU event]
  nmem0/noopstat/                                    [Kernel PMU event]
  nmem0/ponsecs/                                     [Kernel PMU event]
  nmem1/cchrhcnt/                                    [Kernel PMU event]
  nmem1/cchwhcnt/                                    [Kernel PMU event]
  nmem1/critrscu/                                    [Kernel PMU event]
  ...
  nmem1/noopstat/                                    [Kernel PMU event]
  nmem1/ponsecs/                                     [Kernel PMU event]

Patch1:
        Introduces the nvdimm_pmu structure, common function for pmu
        register along with callback routine check.
Pacth2
        Add code in arch/powerpc/platform/pseries/papr_scm.c to expose
        nmem* pmu. It fills in the nvdimm_pmu structure with event attrs
        and event callback functions and then registers the pmu by adding
        callback to register_nvdimm_pmu.
Patch3:
        Sysfs documentation patch
Patch4:
        Adds cpuhotplug support.

Kajol Jain (4):
  drivers/nvdimm: Add perf interface to expose nvdimm performance stats
  powerpc/papr_scm: Add perf interface support
  powerpc/papr_scm: Document papr_scm sysfs event format entries
  powerpc/papr_scm: Add cpu hotplug support for nvdimm pmu device

 Documentation/ABI/testing/sysfs-bus-papr-pmem |  31 ++
 arch/powerpc/include/asm/device.h             |   5 +
 arch/powerpc/platforms/pseries/papr_scm.c     | 346 +++++++++++++++++-
 drivers/nvdimm/Makefile                       |   1 +
 drivers/nvdimm/nd_perf.c                      | 111 ++++++
 include/linux/nd.h                            |  31 ++
 6 files changed, 524 insertions(+), 1 deletion(-)
 create mode 100644 drivers/nvdimm/nd_perf.c

-- 
2.27.0