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From: Dan Williams <dan.j.williams@intel.com>
Date: Wed, 27 May 2020 17:55:14 -0700
Message-ID: <CAPcyv4iTNK1ixzBRkm=09mHfrWzmd97HE4v-M2K5Uz0cKKT=3Q@mail.gmail.com>
Subject: Re: Feedback requested: Exposing NVDIMM performance statistics in a
 generic way
To: Vaibhav Jain <vaibhav@linux.ibm.com>
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CC: linux-nvdimm <linux-nvdimm@lists.01.org>, "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>, Alastair D'Silva <alastair@d-silva.org>
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On Wed, May 27, 2020 at 12:24 PM Dan Williams <dan.j.williams@intel.com> wrote:
[..]
> > This was done by adding two new dimm-ops callbacks that were
> > implemented by the papr_scm implementation within libndctl. These
> > callbacks are invoked by newly introduce code in 'util/json-smart.c'
> > that format the returned stats from these new dimm-ops and transform
> > them into a json-object to later presentation. I would request you to
> > look at RFC patch-set[2] to understand the implementation details.
>
> I'm ok to add some stats to ndctl, but I want ndctl to be limited to
> general statistics and not performance counters. Performance counters
> and performance events should be abstracted through perf where
> possible.

Another aspect that helps common statistics is to expose them in
sysfs. I'm going to go review your proposed ioctl mechanism, but I
would hope that is reserved for multi-field command payloads that need
to be sent as a unit rather than statistics retrieval that is amenable
to a sysfs interface.
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