Re: [PATCH RFC 0/6] Add metrics for neoverse-n2

Jing Zhang
2022-11-19T03:30:44Z

在 2022/11/16 下午7:19, James Clark 写道:
>
>
> On 31/10/2022 11:11, Jing Zhang wrote:
>> This series add six metricgroups for neoverse-n2, among which, the
>> formula of topdown L1 is from the document:
>> https://documentation-service.arm.com/static/60250c7395978b529036da86?token=
>>
>> Since neoverse-n2 does not yet support topdown L2, metricgroups such
>> as Cache, TLB, Branch, InstructionsMix, and PEutilization are added to
>> help further analysis of performance bottlenecks.
>>
>
> Hi Jing,
>
> Thanks for working on this, these metrics look ok to me in general,
> although we're currently working on publishing standardised metrics
> across all new cores as part of a new project in Arm. This will include
> N2, and our ones are very similar (or almost identical) to yours,
> barring slightly different group names, metric names, and differences in
> things like outputting topdown metrics as percentages.
>
> We plan to publish our standard metrics some time in the next 2 months.
> Would you consider holding off on merging this change so that we have
> consistant group names and units going forward? Otherwise N2 would be
> the odd one out. I will send you the metrics when they are ready, and we
> will have a script to generate perf jsons from them, so you can review.
>
> We also have a slightly different forumula for one of the top down
> metrics which I think would be slightly more accurate. We don't have
> anything for your "PE utilization" metrics, which I can raise
> internally. It could always be added to perf on top of the standardised
> ones if we don't add it to our standard ones.
>
> Thanks
> James
>

Hi James,

Regarding the arm n2 standard metrics last time, is my understanding correct,
and does it meet your meaning? If so, may I ask when you will send me the
standards you formulate so that I can align with you in time over my patchset.
Please communicate this matter so that we can understand each other's schedule.

Thanks,
Jing

>> with this series on neoverse-n2:
>>
>> $./perf list metricgroup
>>
>> List of pre-defined events (to be used in -e):
>>
>>
>> Metric Groups:
>>
>> Branch
>> Cache
>> InstructionMix
>> PEutilization
>> TLB
>> TopDownL1
>>
>>
>> $./perf list
>>
>> ...
>> Metric Groups:
>>
>> Branch:
>> branch_miss_pred_rate
>> [The rate of branches mis-predited to the overall branches]
>> branch_mpki
>> [The rate of branches mis-predicted per kilo instructions]
>> branch_pki
>> [The rate of branches retired per kilo instructions]
>> Cache:
>> l1d_cache_miss_rate
>> [The rate of L1 D-Cache misses to the overall L1 D-Cache]
>> l1d_cache_mpki
>> [The rate of L1 D-Cache misses per kilo instructions]
>> ...
>>
>>
>> $sudo ./perf stat -a -M TLB sleep 1
>>
>> Performance counter stats for 'system wide':
>>
>> 35,861,936 L1I_TLB # 0.00 itlb_walk_rate (74.91%)
>> 5,661 ITLB_WALK (74.91%)
>> 97,279,240 INST_RETIRED # 0.07 itlb_mpki (74.91%)
>> 6,851 ITLB_WALK (74.91%)
>> 26,391 DTLB_WALK # 0.00 dtlb_walk_rate (75.07%)
>> 35,585,545 L1D_TLB (75.07%)
>> 85,923,244 INST_RETIRED # 0.35 dtlb_mpki (75.11%)
>> 29,992 DTLB_WALK (75.11%)
>>
>> 1.003450755 seconds time elapsed
>>
>>
>> Jing Zhang (6):
>> perf vendor events arm64: Add topdown L1 metrics for neoverse-n2
>> perf vendor events arm64: Add TLB metrics for neoverse-n2
>> perf vendor events arm64: Add cache metrics for neoverse-n2
>> perf vendor events arm64: Add branch metrics for neoverse-n2
>> perf vendor events arm64: Add PE utilization metrics for neoverse-n2
>> perf vendor events arm64: Add instruction mix metrics for neoverse-n2
>>
>> .../arch/arm64/arm/neoverse-n2/metrics.json | 247 +++++++++++++++++++++
>> 1 file changed, 247 insertions(+)
>> create mode 100644 tools/perf/pmu-events/arch/arm64/arm/neoverse-n2/metrics.json
>>