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From:   Ian Rogers <irogers@google.com>
Date:   Fri, 24 Mar 2023 00:15:27 -0700
Message-ID: <CAP-5=fX5KaQE+P5X+jBt9uFymkjWbUi_0dgq2w=18jX8vVQ1XQ@mail.gmail.com>
Subject: Re: [PATCH v2 8/9] perf metrics: Add has_optane literal
To:     Dan Williams <dan.j.williams@intel.com>
Cc:     "Liang, Kan" <kan.liang@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Zhengjun Xing <zhengjun.xing@linux.intel.com>,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
        Edward Baker <edward.baker@intel.com>, perry.taylor@intel.com,
        caleb.biggers@intel.com, samantha.alt@intel.com,
        weilin.wang@intel.com
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On Thu, Mar 23, 2023 at 1:44=E2=80=AFPM Dan Williams <dan.j.williams@intel.=
com> wrote:
>
> Liang, Kan wrote:
> >
> >
> > On 2023-03-23 3:20 p.m., Ian Rogers wrote:
> > > Add literal so that if optane memory isn't installed we can record
> > > fewer events.
> >
> > I think we call it pmem (Persistent Memory) everywhere in the Linux
> > code. Maybe we should use #has_pmem instead?
>
> That makes sense especially because has_optane implies more precision
> than the the check is performing. In general Optane is probably the
> widest deployed NVDIMM type, but this check will succeed with battery
> backed NVDIMMs and emulated PMEM in VMs which I think is perfectly ok
> for making a default event record decision.

Thanks, I'll change this in v3.

Ian