Re: [PATCH v6 0/4] Add perf interface to expose nvdimm

On Thu, Feb 17, 2022 at 8:34 AM Kajol Jain [off-list ref] wrote:

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 cpumask, nvdimm device
pointer and pmu event functions like event_init/add/read/del.
User could use the standard perf tool to access perf events
exposed via pmu.

Interface also defines supported event list, config fields for the
event attributes and their corresponding bit values which are exported
via sysfs. Patch 3 exposes IBM pseries platform nmem* device
performance stats using this interface.

Result from power9 pseries lpar with 2 nvdimm device:

Ex: List all event by perf list

command:# perf list nmem

  nmem0/cache_rh_cnt/                                [Kernel PMU event]
  nmem0/cache_wh_cnt/                                [Kernel PMU event]
  nmem0/cri_res_util/                                [Kernel PMU event]
  nmem0/ctl_res_cnt/                                 [Kernel PMU event]
  nmem0/ctl_res_tm/                                  [Kernel PMU event]
  nmem0/fast_w_cnt/                                  [Kernel PMU event]
  nmem0/host_l_cnt/                                  [Kernel PMU event]
  nmem0/host_l_dur/                                  [Kernel PMU event]
  nmem0/host_s_cnt/                                  [Kernel PMU event]
  nmem0/host_s_dur/                                  [Kernel PMU event]
  nmem0/med_r_cnt/                                   [Kernel PMU event]
  nmem0/med_r_dur/                                   [Kernel PMU event]
  nmem0/med_w_cnt/                                   [Kernel PMU event]
  nmem0/med_w_dur/                                   [Kernel PMU event]
  nmem0/mem_life/                                    [Kernel PMU event]
  nmem0/poweron_secs/                                [Kernel PMU event]
  ...
  nmem1/mem_life/                                    [Kernel PMU event]
  nmem1/poweron_secs/                                [Kernel PMU event]

Patch1:
        Introduces the nvdimm_pmu structure
Patch2:
        Adds common interface to add arch/platform specific data
        includes nvdimm device pointer, pmu data along with
        pmu event functions. It also defines supported event list
        and adds attribute groups for format, events and cpumask.
        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 pmu name,
        capabilities, cpumask and event functions and then registers
        the pmu by adding callbacks to register_nvdimm_pmu.
Patch4:
        Sysfs documentation patch

Changelog
---
Resend v5 -> v6
- No logic change, just a rebase to latest upstream and
  tested the patchset.

- Link to the patchset Resend v5: https://lkml.org/lkml/2021/11/15/3979

v5 -> Resend v5
- Resend the patchset

- Link to the patchset v5: https://lkml.org/lkml/2021/9/28/643

v4 -> v5:
- Remove multiple variables defined in nvdimm_pmu structure include
  name and pmu functions(event_int/add/del/read) as they are just
  used to copy them again in pmu variable. Now we are directly doing
  this step in arch specific code as suggested by Dan Williams.

- Remove attribute group field from nvdimm pmu structure and
  defined these attribute groups in common interface which
  includes format, event list along with cpumask as suggested by
  Dan Williams.
  Since we added static defination for attrbute groups needed in
  common interface, removes corresponding code from papr.

- Add nvdimm pmu event list with event codes in the common interface.

- Remove Acked-by/Reviewed-by/Tested-by tags as code is refactored
  to handle review comments from Dan.

I don't think review comments should invalidate the Acked-by tags in
this case. Nothing fundamentally changed in the approach, and I would
like to have the perf ack before taking this through the nvdimm tree.

Otherwise this looks good to me.

Peter, might you have a chance to re-Ack this series, or any concerns
about me retrieving those Acks from the previous postings?