[PATCH v8 0/9] Add metrics for neoverse-n2-v2

Jing Zhang
2023-01-17T07:30:03Z

Changes since v7:
- Change pmu_core__find_same to pmu__find_core_pmu as suggested by Ian.
- Returned NAN when can't find a pmu or the value from */caps/slots is
zero, in perf_pmu__cpu_slots_per_cycle, as suggested by John.
- Link: https://lore.kernel.org/all/1673601740-122788-1-git-send-email-renyu.zj@linux.alibaba.com/

Changes since v6:
- Split patch 1 into 3 smaller patches as suggested by Ian.
- Change perf_pmu__get_slots to perf_pmu__cpu_slots_per_cycle,
per John's suggestion;
- Return NAN instead of 0 in perf_pmu__cpu_slots_per_cycle weak
function, per John's suggestion;
- Factor out pmu_core__find_same function, per John's suggestion.
- Link: https://lore.kernel.org/all/1673017529-1429208-1-git-send-email-renyu.zj@linux.alibaba.com/

Changes since v5:
- Add common topdownL1 metrics in sbsa.json as suggested by John;
- Correct PKI/MPKI ScaleUnit to 1PKI/1MPKI;
- Link: https://lore.kernel.org/all/1672745976-2800146-1-git-send-email-renyu.zj@linux.alibaba.com/

Changes since v4:
- Add MPKI/PKI “ScaleUnit”;
- Add acked-by from Ian Rogers;
- Link: https://lore.kernel.org/all/1671799045-1108027-1-git-send-email-renyu.zj@linux.alibaba.com/

Changes since v3:
- Add ipc_rate metric;
- Drop the PublicDescription;
- Describe PEutilization metrics in more detail;
- Link: https://lore.kernel.org/all/1669310088-13482-1-git-send-email-renyu.zj@linux.alibaba.com/

Changes since v2:
- Correct the furmula of Branch metrics;
- Add more PE utilization metrics;
- Add more TLB metrics;
- Add “ScaleUnit” for some metrics;
- Add a newline at the end of the file;
- Link: https://lore.kernel.org/all/1668411720-3581-1-git-send-email-renyu.zj@linux.alibaba.com/

Changes since v1:
- Corrected formula for topdown L1 due to wrong counts for stall_slot
and stall_slot_frontend;
- Link: https://lore.kernel.org/all/1667214694-89839-1-git-send-email-renyu.zj@linux.alibaba.com/

This series does the following things:

The slots in each architecture may be different, so add #slots literal
to obtain the slots of different architectures, and the #slots can be
applied in the topdown metric. Currently, The #slots just support for
arm64, and other architectures will return NAN.

The metrics of topdown L1 are from ARM sbsa7.0 platform design doc[0],
D37-38, which are standard. So put them in the common file sbsa.json of
arm64 and add general metric support, so that other cores besides n2/v2
can also be reused.

Then add topdownL1 metric for neoverse-n2-v2, and due to the wrong count
of stall_slot and stall_slot_frontend on neoverse-n2, the real stall_slot
and real stall_slot_frontend need to subtract cpu_cycles, so overwrite
the "MetricExpr" for neoverse-n2.
Reference from ARM neoverse-n2 errata notice [1], D117.

Since neoverse-n2/neoverse-v2 does not yet support topdown L2, metricgroups
such as Cache, TLB, Branch, InstructionsMix, and PEutilization will be added
to further analysis of performance bottlenecks in the following patches.
Reference from ARM PMU guide [2][3].

[0] https://documentation-service.arm.com/static/60250c7395978b529036da86?token=
[1] https://documentation-service.arm.com/static/636a66a64e6cf12278ad89cb?token=
[2] https://documentation-service.arm.com/static/628f8fa3dfaf015c2b76eae8?token=
[3] https://documentation-service.arm.com/static/62cfe21e31ea212bb6627393?token=

Tested in neoverse-n2:

$./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 -M TLB false_sharing 2

Performance counter stats for 'false_sharing 2':

29,940 L2D_TLB # 20.0 % l2_tlb_miss_rate (42.36%)
5,998 L2D_TLB_REFILL (42.36%)
1,753 L1I_TLB_REFILL # 0.1 % l1i_tlb_miss_rate (43.17%)
2,173,957 L1I_TLB (43.17%)
327,944,763 L1D_TLB # 0.0 % l1d_tlb_miss_rate (43.98%)
22,485 L1D_TLB_REFILL (43.98%)
497,210 L1I_TLB # 0.0 % itlb_walk_rate (44.83%)
28 ITLB_WALK (44.83%)
821,488,762 INST_RETIRED # 0.0 MPKI itlb_mpki (43.97%)
122 ITLB_WALK (43.97%)
744 DTLB_WALK # 0.0 % dtlb_walk_rate (43.01%)
263,913,146 L1D_TLB (43.01%)
779,073,875 INST_RETIRED # 0.0 MPKI dtlb_mpki (42.07%)
1,050 DTLB_WALK (42.07%)

0.435864901 seconds time elapsed

1.201384000 seconds user
0.000000000 seconds sys

$sudo ./perf stat -M TopDownL1 false_sharing 2

Performance counter stats for 'false_sharing 2':

3,408,960,257 cpu_cycles # 0.0 % bad_speculation
# 5.1 % retiring (66.79%)
19,576,079,610 stall_slot (66.79%)
877,673,452 op_spec (66.79%)
876,324,270 op_retired (66.79%)
3,406,548,064 cpu_cycles # 26.7 % frontend_bound (67.08%)
7,961,814,801 stall_slot_frontend (67.08%)
3,415,528,440 cpu_cycles # 68.8 % backend_bound (66.43%)
11,746,647,747 stall_slot_backend (66.43%)

0.455229807 seconds time elapsed

1.243216000 seconds user
0.000000000 seconds sys

$sudo ./perf stat -M branch sleep 1

Performance counter stats for 'sleep 1':

901,495 INST_RETIRED # 223.6 PKI branch_pki
201,603 BR_RETIRED
901,495 INST_RETIRED # 10.0 MPKI branch_mpki
9,004 BR_MIS_PRED_RETIRED
9,004 BR_MIS_PRED_RETIRED # 4.5 % branch_miss_pred_rate
201,603 BR_RETIRED

1.000794467 seconds time elapsed

0.000905000 seconds user
0.000000000 seconds sys

Jing Zhang (9):
perf pmu: Add #slots literal support for arm64
perf jevent: Add general metrics support
perf vendor events arm64: Add common topdown L1 metrics
perf vendor events arm64: Add topdown L1 metrics for neoverse-n2-v2
perf vendor events arm64: Add TLB metrics for neoverse-n2-v2
perf vendor events arm64: Add cache metrics for neoverse-n2-v2
perf vendor events arm64: Add branch metrics for neoverse-n2-v2
perf vendor events arm64: Add PE utilization metrics for
neoverse-n2-v2
perf vendor events arm64: Add instruction mix metrics for
neoverse-n2-v2

tools/perf/arch/arm64/util/pmu.c | 35 ++-
.../arch/arm64/arm/neoverse-n2-v2/metrics.json | 273 +++++++++++++++++++++
tools/perf/pmu-events/arch/arm64/sbsa.json | 30 +++
tools/perf/pmu-events/jevents.py | 2 +
tools/perf/util/expr.c | 5 +
tools/perf/util/pmu.c | 6 +
tools/perf/util/pmu.h | 1 +
7 files changed, 350 insertions(+), 2 deletions(-)
create mode 100644 tools/perf/pmu-events/arch/arm64/arm/neoverse-n2-v2/metrics.json
create mode 100644 tools/perf/pmu-events/arch/arm64/sbsa.json

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1.8.3.1