Adding stat-cpi.py as an example of how to do stat scripting.
It computes the CPI metrics from cycles and instructions events.
The CPI is based performance metric showing the Cycles Per Instructions
ratio, which helps to identify cycles-hungry code.
Following stat record/report/script combinations could be used:
- get CPI for given workload
$ perf stat -e cycles,instructions record ls
SNIP
Performance counter stats for 'ls':
2,904,431 cycles
3,346,878 instructions # 1.15 insns per cycle
0.001782686 seconds time elapsed
$ perf script -s ./scripts/python/stat-cpi.py
0.001783: cpu -1, thread -1 -> cpi 0.867803 (2904431/3346878)
$ perf stat -e cycles,instructions record ls | perf script -s ./scripts/python/stat-cpi.py
SNIP
0.001730: cpu -1, thread -1 -> cpi 0.869026 (2928292/3369627)
- get CPI systemwide:
$ perf stat -e cycles,instructions -a -I 1000 record sleep 3
# time counts unit events
1.000158618 594,274,711 cycles (100.00%)
1.000158618 441,898,250 instructions
2.000350973 567,649,705 cycles (100.00%)
2.000350973 432,669,206 instructions
3.000559210 561,940,430 cycles (100.00%)
3.000559210 420,403,465 instructions
3.000670798 780,105 cycles (100.00%)
3.000670798 326,516 instructions
$ perf script -s ./scripts/python/stat-cpi.py
1.000159: cpu -1, thread -1 -> cpi 1.344823 (594274711/441898250)
2.000351: cpu -1, thread -1 -> cpi 1.311972 (567649705/432669206)
3.000559: cpu -1, thread -1 -> cpi 1.336669 (561940430/420403465)
3.000671: cpu -1, thread -1 -> cpi 2.389178 (780105/326516)
$ perf stat -e cycles,instructions -a -I 1000 record sleep 3 | perf script -s ./scripts/python/stat-cpi.py
1.000202: cpu -1, thread -1 -> cpi 1.035091 (940778881/908885530)
2.000392: cpu -1, thread -1 -> cpi 1.442600 (627493992/434974455)
3.000545: cpu -1, thread -1 -> cpi 1.353612 (741463930/547766890)
3.000622: cpu -1, thread -1 -> cpi 2.642110 (784083/296764)
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Kan Liang <kan.liang@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1452077397-31958-4-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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