[PATCH v2 0/4] Add perf interface to expose nvdimm

[Kajol Jain]

Patchset adds performance stats reporting support for nvdimm.
Added interface includes support for pmu register/unregister
functions. A structure is added called nvdimm_pmu to be used for
adding arch/platform specific data such as supported events, cpumask
pmu event functions like event_init/add/read/del.
User could use the standard perf tool to access perf
events exposed via pmu.

Added implementation 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
Patch2:
	Adds common interface to add arch/platform specific data
	includes supported events, pmu event functions. It also
	adds code for cpu hotplug support.
Patch3:
        Add code in arch/powerpc/platform/pseries/papr_scm.c to expose
        nmem* pmu. It fills in the nvdimm_pmu structure with event attrs
        cpumask andevent functions and then registers the pmu by adding
        callbacks to register_nvdimm_pmu.
Patch4:
        Sysfs documentation patch

Changelog
---
PATCH v1 -> PATCH v2
- Fix hotplug code by adding pmu migration call
  incase current designated cpu got offline. As
  pointed by Peter Zijlstra.

- Removed the retun -1 part from cpu hotplug offline
  function.

- Link to the previous patchset : https://lkml.org/lkml/2021/6/8/500
---
Kajol Jain (4):
  drivers/nvdimm: Add nvdimm pmu structure
  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

 Documentation/ABI/testing/sysfs-bus-papr-pmem |  31 ++
 arch/powerpc/include/asm/device.h             |   5 +
 arch/powerpc/platforms/pseries/papr_scm.c     | 365 ++++++++++++++++++
 drivers/nvdimm/Makefile                       |   1 +
 drivers/nvdimm/nd_perf.c                      | 230 +++++++++++
 include/linux/nd.h                            |  46 +++
 6 files changed, 678 insertions(+)
 create mode 100644 drivers/nvdimm/nd_perf.c

-- 
2.27.0