Messages in this thread Patch in this message |  | | Subject | Re: [PATCH 6/9] perf report: Support instruction latency | From | "Liang, Kan" <> | Date | Mon, 8 Feb 2021 08:50:14 -0500 |
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On 2/6/2021 3:09 AM, Namhyung Kim wrote: > On Fri, Feb 5, 2021 at 11:38 PM Liang, Kan <kan.liang@linux.intel.com> wrote: >> >> On 2/5/2021 6:08 AM, Namhyung Kim wrote: >>> On Wed, Feb 3, 2021 at 5:14 AM <kan.liang@linux.intel.com> wrote: >>>> >>>> From: Kan Liang <kan.liang@linux.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? >
The instruction latency field is an extension of the weight field, so I follow the same way to name the field. I still think we should make the naming consistency.
To address the confusion, I think we may update the document for both the weight and the instruction latency fields.
How about the below patch?
From d5e80f541cb7288b24a7c5661ae5faede4747807 Mon Sep 17 00:00:00 2001 From: Kan Liang <kan.liang@linux.intel.com> Date: Mon, 8 Feb 2021 05:27:03 -0800 Subject: [PATCH] perf documentation: Add comments to the local/global weight related fields
Current 'local' and 'global' prefix is confusing for the weight related fields, e.g., weight, instruction latency.
Add comments to clarify. 'global' means total weight/instruction latency sum. 'local' means average weight/instruction latency per sample
Signed-off-by: Kan Liang <kan.liang@linux.intel.com> --- tools/perf/Documentation/perf-report.txt | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt index f546b5e..acc1c1d 100644 --- a/tools/perf/Documentation/perf-report.txt +++ b/tools/perf/Documentation/perf-report.txt @@ -92,8 +92,9 @@ OPTIONS - srcfile: file name of the source file of the samples. Requires dwarf information. - weight: Event specific weight, e.g. memory latency or transaction - abort cost. This is the global weight. - - local_weight: Local weight version of the weight above. + abort cost. This is the global weight (total weight sum). + - local_weight: Local weight (average weight per sample) version of the + weight above. - cgroup_id: ID derived from cgroup namespace device and inode numbers. - cgroup: cgroup pathname in the cgroupfs. - transaction: Transaction abort flags. @@ -110,8 +111,9 @@ OPTIONS --time-quantum (default 100ms). Specify with overhead and before it. - code_page_size: the code page size of sampled code address (ip) - ins_lat: Instruction latency in core cycles. This is the global instruction - latency - - local_ins_lat: Local instruction latency version + latency (total instruction latency sum) + - local_ins_lat: Local instruction latency (average instruction latency per + sample) version
By default, comm, dso and symbol keys are used. (i.e. --sort comm,dso,symbol) -- 2.7.4
Thanks, Kan
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