linux-kernel - Re: [PATCH 6/9] perf report: Support instruction latency

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Date:   Sat, 6 Feb 2021 17:09:33 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     "Liang, Kan" <kan.liang@...ux.intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Stephane Eranian <eranian@...gle.com>,
        Jiri Olsa <jolsa@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
        Yao Jin <yao.jin@...ux.intel.com>, maddy@...ux.vnet.ibm.com
Subject: Re: [PATCH 6/9] perf report: Support instruction latency

On Fri, Feb 5, 2021 at 11:38 PM Liang, Kan <kan.liang@...ux.intel.com> wrote:
>
> On 2/5/2021 6:08 AM, Namhyung Kim wrote:
> > On Wed, Feb 3, 2021 at 5:14 AM <kan.liang@...ux.intel.com> wrote:
> >>
> >> From: Kan Liang <kan.liang@...ux.intel.com>
> >>
> >> The instruction latency information can be recorded on some platforms,
> >> e.g., the Intel Sapphire Rapids server. With both memory latency
> >> (weight) and the new instruction latency information, users can easily
> >> locate the expensive load instructions, and also understand the time
> >> spent in different stages. The users can optimize their applications
> >> in different pipeline stages.
> >>
> >> The 'weight' field is shared among different architectures. Reusing the
> >> 'weight' field may impacts other architectures. Add a new field to store
> >> the instruction latency.
> >>
> >> Like the 'weight' support, introduce a 'ins_lat' for the global
> >> instruction latency, and a 'local_ins_lat' for the local instruction
> >> latency version.
> >
> > Could you please clarify the difference between the global latency
> > and the local latency?
> >
>
> The global means the total latency.
> The local means average latency, aka total / number of samples.

Thanks for the explanation, but I think it's confusing.
Why not call it just total_latency and avg_latency?

Thanks,
Namhyung