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

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Message-ID: <CAPcyv4jwpMbz0woftSfm3EO05pr3ZG9rVMJCkYVsapKYSOn3xw@mail.gmail.com>
Date:   Fri, 18 Feb 2022 10:06:36 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Kajol Jain <kjain@...ux.ibm.com>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Linux NVDIMM <nvdimm@...ts.linux.dev>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Weiny, Ira" <ira.weiny@...el.com>,
        Vishal L Verma <vishal.l.verma@...el.com>,
        Santosh Sivaraj <santosh@...six.org>, maddy@...ux.ibm.com,
        rnsastry@...ux.ibm.com,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        atrajeev@...ux.vnet.ibm.com, Vaibhav Jain <vaibhav@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v6 0/4] Add perf interface to expose nvdimm

On Thu, Feb 17, 2022 at 8:34 AM Kajol Jain <kjain@...ux.ibm.com> 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?