Re: [RFC 1/4] drivers/nvdimm: Add perf interface to expose nvdimm performance stats
On 5/14/21 5:17 PM, Peter Zijlstra wrote:
> On Thu, May 13, 2021 at 05:56:14PM +0530, kajoljain wrote:
>
>> But yes the current read/add/del functions are not adding value. We
>> could add an arch/platform specific function which could handle the
>> capturing of the counter data and do the rest of the operation here,
>> is this approach better?
>
> Right; have your register_nvdimm_pmu() set pmu->{add,del,read} to
> nd_pmu->{add,del,read} directly, don't bother with these intermediates.
> Also you can WARN_ON_ONCE() if any of them are NULL and fail
> registration at that point.
>
Hi Peter,
I will make all required changes and send next version of this patchset
soon.
Thanks,
Kajol Jain
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Re: [RFC 1/4] drivers/nvdimm: Add perf interface to expose nvdimm performance stats
On Thu, May 13, 2021 at 05:56:14PM +0530, kajoljain wrote:
> But yes the current read/add/del functions are not adding value. We
> could add an arch/platform specific function which could handle the
> capturing of the counter data and do the rest of the operation here,
> is this approach better?
Right; have your register_nvdimm_pmu() set pmu->{add,del,read} to
nd_pmu->{add,del,read} directly, don't bother with these intermediates.
Also you can WARN_ON_ONCE() if any of them are NULL and fail
registration at that point.
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Re: [RFC 1/4] drivers/nvdimm: Add perf interface to expose nvdimm performance stats
On 5/12/21 10:57 PM, Peter Zijlstra wrote:
> On Wed, May 12, 2021 at 10:08:21PM +0530, Kajol Jain wrote:
>> +static void nvdimm_pmu_read(struct perf_event *event)
>> +{
>> +struct nvdimm_pmu *nd_pmu = to_nvdimm_pmu(event->pmu);
>> +
>> +/* jump to arch/platform specific callbacks if any */
>> +if (nd_pmu && nd_pmu->read)
>> +nd_pmu->read(event, nd_pmu->dev);
>> +}
>> +
>> +static void nvdimm_pmu_del(struct perf_event *event, int flags)
>> +{
>> +struct nvdimm_pmu *nd_pmu = to_nvdimm_pmu(event->pmu);
>> +
>> +/* jump to arch/platform specific callbacks if any */
>> +if (nd_pmu && nd_pmu->del)
>> +nd_pmu->del(event, flags, nd_pmu->dev);
>> +}
>> +
>> +static int nvdimm_pmu_add(struct perf_event *event, int flags)
>> +{
>> +struct nvdimm_pmu *nd_pmu = to_nvdimm_pmu(event->pmu);
>> +
>> +if (flags & PERF_EF_START)
>> +/* jump to arch/platform specific callbacks if any */
>> +if (nd_pmu && nd_pmu->add)
>> +return nd_pmu->add(event, flags, nd_pmu->dev);
>> +return 0;
>> +}
>
> What's the value add here? Why can't you directly set driver pointers? I
> also don't really believe ->{add,del,read} can be optional and still
> have a sane driver.
>
Hi Peter,
The intend for adding these callbacks is to give flexibility to the
arch/platform specific driver code to use its own routine for getting
counter data or specific checks/operations. Arch/platform driver code
would have different method to get the counter data like IBM pseries
nmem* device which uses a hypervisor call(hcall).
But yes the current read/add/del functions are not adding value. We
could add an arch/platform specific function which could handle the
capturing of the counter data and do the rest of the operation here,
is this approach better?
Thanks,
Kajol Jain
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Re: [RFC 1/4] drivers/nvdimm: Add perf interface to expose nvdimm performance stats
On Wed, May 12, 2021 at 10:08:21PM +0530, Kajol Jain wrote:
> +static void nvdimm_pmu_read(struct perf_event *event)
> +{
> + struct nvdimm_pmu *nd_pmu = to_nvdimm_pmu(event->pmu);
> +
> + /* jump to arch/platform specific callbacks if any */
> + if (nd_pmu && nd_pmu->read)
> + nd_pmu->read(event, nd_pmu->dev);
> +}
> +
> +static void nvdimm_pmu_del(struct perf_event *event, int flags)
> +{
> + struct nvdimm_pmu *nd_pmu = to_nvdimm_pmu(event->pmu);
> +
> + /* jump to arch/platform specific callbacks if any */
> + if (nd_pmu && nd_pmu->del)
> + nd_pmu->del(event, flags, nd_pmu->dev);
> +}
> +
> +static int nvdimm_pmu_add(struct perf_event *event, int flags)
> +{
> + struct nvdimm_pmu *nd_pmu = to_nvdimm_pmu(event->pmu);
> +
> + if (flags & PERF_EF_START)
> + /* jump to arch/platform specific callbacks if any */
> + if (nd_pmu && nd_pmu->add)
> + return nd_pmu->add(event, flags, nd_pmu->dev);
> + return 0;
> +}
What's the value add here? Why can't you directly set driver pointers? I
also don't really believe ->{add,del,read} can be optional and still
have a sane driver.
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