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Subject: Re: [PATCH v5 0/4] Add perf interface to expose nvdimm
To:     mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org,
        nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org,
        peterz@infradead.org, dan.j.williams@intel.com,
        ira.weiny@intel.com, vishal.l.verma@intel.com
Cc:     maddy@linux.ibm.com, santosh@fossix.org,
        aneesh.kumar@linux.ibm.com, vaibhav@linux.ibm.com,
        atrajeev@linux.vnet.ibm.com, tglx@linutronix.de,
        rnsastry@linux.ibm.com
References: <20210928124200.146331-1-kjain@linux.ibm.com>
From:   kajoljain <kjain@linux.ibm.com>
Message-ID: <b54072ad-4d71-ff6d-7c63-0c1395e1d8f8@linux.ibm.com>
Date:   Wed, 13 Oct 2021 15:45:15 +0530
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Hi Dan,
   Any comments on this patch-set?

Thanks,
Kajol Jain

On 9/28/21 6:11 PM, Kajol Jain 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
> ---
> 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.
> 
> - Make nvdimm_pmu_free_hotplug_memory function static as reported
>   by kernel test robot, also add corresponding Reported-by tag.
> 
> - Link to the patchset v4: https://lkml.org/lkml/2021/9/3/45
> 
> v3 -> v4
> - Rebase code on top of current papr_scm code without any logical
>   changes.
> 
> - Added Acked-by tag from Peter Zijlstra and Reviewed by tag
>   from Madhavan Srinivasan.
> 
> - Link to the patchset v3: https://lkml.org/lkml/2021/6/17/605
> 
> v2 -> v3
> - Added Tested-by tag.
> 
> - Fix nvdimm mailing list in the ABI Documentation.
> 
> - Link to the patchset v2: https://lkml.org/lkml/2021/6/14/25
> 
> v1 -> 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 patchset v1: 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
>   docs: ABI: sysfs-bus-nvdimm: Document sysfs event format entries for
>     nvdimm pmu
> 
>  Documentation/ABI/testing/sysfs-bus-nvdimm |  35 +++
>  arch/powerpc/include/asm/device.h          |   5 +
>  arch/powerpc/platforms/pseries/papr_scm.c  | 225 ++++++++++++++
>  drivers/nvdimm/Makefile                    |   1 +
>  drivers/nvdimm/nd_perf.c                   | 328 +++++++++++++++++++++
>  include/linux/nd.h                         |  41 +++
>  6 files changed, 635 insertions(+)
>  create mode 100644 drivers/nvdimm/nd_perf.c
>