Power10 Performance Monitoring Unit (PMU) provides events to understand
stall cycles of different pipeline stages. These events along with
completed instructions provides useful metrics for application tuning.
Patch implements the JSON changes to collect counter statistics to
present the high level CPI stall breakdown metrics. New metric group is
named as "CPI_STALL_RATIO" and this new metric group presents these
stall metrics:
- DISPATCHED_CPI ( Dispatch stall cycles per insn )
- ISSUE_STALL_CPI ( Issue stall cycles per insn )
- EXECUTION_STALL_CPI ( Execution stall cycles per insn )
- COMPLETION_STALL_CPI ( Completition stall cycles per insn )
To avoid multipling of events, PM_RUN_INST_CMPL event has been modified
to use PMC5(performance monitoring counter5) instead of PMC4. This
change is needed, since completion stall event is using PMC4.
Usage example:
./perf stat --metric-no-group -M CPI_STALL_RATIO <workload>
Performance counter stats for 'workload':
63,056,817,982 PM_CMPL_STALL # 0.28 COMPLETION_STALL_CPI
1,743,988,038,896 PM_ISSUE_STALL # 7.73 ISSUE_STALL_CPI
225,597,495,030 PM_RUN_INST_CMPL # 6.18 DISPATCHED_CPI
# 37.48 EXECUTION_STALL_CPI
1,393,916,546,654 PM_DISP_STALL_CYC
8,455,376,836,463 PM_EXEC_STALL
"--metric-no-group" is used for forcing PM_RUN_INST_CMPL to be scheduled
in all group for more accuracy.
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Disha Goel <disgoel@linux.ibm.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nageswara R Sastry <rnsastry@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230216061240.18067-1-atrajeev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
