linux-kernel - Re: [PATCH v7 0/4] Add perf interface to expose nvdimm

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Message-ID: <4a2164f4-0667-ae6c-758a-9bcaca43410f@linux.ibm.com>
Date:   Mon, 7 Mar 2022 12:50:22 +0530
From:   Madhavan Srinivasan <maddy@...ux.ibm.com>
To:     Kajol Jain <kjain@...ux.ibm.com>, mpe@...erman.id.au,
        linuxppc-dev@...ts.ozlabs.org, nvdimm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        dan.j.williams@...el.com, ira.weiny@...el.com,
        vishal.l.verma@...el.com
Cc:     santosh@...six.org, rnsastry@...ux.ibm.com,
        aneesh.kumar@...ux.ibm.com, atrajeev@...ux.vnet.ibm.com,
        vaibhav@...ux.ibm.com, tglx@...utronix.de
Subject: Re: [PATCH v7 0/4] Add perf interface to expose nvdimm


On 2/25/22 20:00, 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:

Patchset looks fine to me.

Reviewed-by: Madhavan Srinivasan <maddy@...ibm.com>


> 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
> ---
> v6 -> v7
> - Add function call to numa_map_to_online_node function inorder to
>    get online numa node. As the node id returned by function dev_to_node
>    can be offline in some scenarios and can create issue in hotplug code
>    as reported by Nageswara R Sastry.
>
> - Add function declaration of perf_pmu_register, perf_pmu_unregister
>    and  perf_pmu_migrate_context functions in nd.h file to resolve
>    the implicit-function-declaration warning as reported by kernel test
>    robot.
>    Link: https://lore.kernel.org/all/202202241242.zqzGkguy-lkp@intel.com/
>
> - Add Tested-by, Acked-by and Reported-by tags from Peter Zijlstra
>    and Nageswara R Sastry.
>
> - Link to the patchset v6: https://lkml.org/lkml/2022/2/17/857
>
> 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.
>
> - 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                         |  44 +++
>   6 files changed, 638 insertions(+)
>   create mode 100644 drivers/nvdimm/nd_perf.c
>