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Ian Rogers authored
The sysfs format files are loaded eagerly in a PMU. Add a flag so that we create the format but only load the contents when necessary. Reduce the size of the value in struct perf_pmu_format and avoid holes so there is no additional space requirement. For "perf stat -e cycles true" this reduces the number of openat calls from 648 to 573 (about 12%). The benchmark pmu scan speed is improved by roughly 5%. Before: $ perf bench internals pmu-scan Computing performance of sysfs PMU event scan for 100 times Average core PMU scanning took: 1061.100 usec (+- 9.965 usec) Average PMU scanning took: 4725.300 usec (+- 260.599 usec) After: $ perf bench internals pmu-scan Computing performance of sysfs PMU event scan for 100 times Average core PMU scanning took: 989.170 usec (+- 6.873 usec) Average PMU scanning took: 4520.960 usec (+- 251.272 usec) Committer testing: On a AMD Ryzen 5950x: Before: $ perf bench internals pmu-scan -i1000 # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 563.466 usec (+- 1.008 usec) Average PMU scanning took: 1619.174 usec (+- 23.627 usec) $ perf stat -r5 perf bench internals pmu-scan -i1000 # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 583.401 usec (+- 2.098 usec) Average PMU scanning took: 1677.352 usec (+- 24.636 usec) # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 553.254 usec (+- 0.825 usec) Average PMU scanning took: 1635.655 usec (+- 24.312 usec) # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 557.733 usec (+- 0.980 usec) Average PMU scanning took: 1600.659 usec (+- 23.344 usec) # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 554.906 usec (+- 0.774 usec) Average PMU scanning took: 1595.338 usec (+- 23.288 usec) # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 551.798 usec (+- 0.967 usec) Average PMU scanning took: 1623.213 usec (+- 23.998 usec) Performance counter stats for 'perf bench internals pmu-scan -i1000' (5 runs): 3276.82 msec task-clock:u # 0.990 CPUs utilized ( +- 0.82% ) 0 context-switches:u # 0.000 /sec 0 cpu-migrations:u # 0.000 /sec 1008 page-faults:u # 307.615 /sec ( +- 0.04% ) 12049614778 cycles:u # 3.677 GHz ( +- 0.07% ) (83.34%) 117507478 stalled-cycles-frontend:u # 0.98% frontend cycles idle ( +- 0.33% ) (83.32%) 27106761 stalled-cycles-backend:u # 0.22% backend cycles idle ( +- 9.55% ) (83.36%) 33294953848 instructions:u # 2.76 insn per cycle # 0.00 stalled cycles per insn ( +- 0.03% ) (83.31%) 6849825049 branches:u # 2.090 G/sec ( +- 0.03% ) (83.37%) 71533903 branch-misses:u # 1.04% of all branches ( +- 0.20% ) (83.30%) 3.3088 +- 0.0302 seconds time elapsed ( +- 0.91% ) $ After: $ perf stat -r5 perf bench internals pmu-scan -i1000 # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 550.702 usec (+- 0.958 usec) Average PMU scanning took: 1566.577 usec (+- 22.747 usec) # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 548.315 usec (+- 0.555 usec) Average PMU scanning took: 1565.499 usec (+- 22.760 usec) # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 548.073 usec (+- 0.555 usec) Average PMU scanning took: 1586.097 usec (+- 23.299 usec) # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 561.184 usec (+- 2.709 usec) Average PMU scanning took: 1567.153 usec (+- 22.548 usec) # Running 'internals/pmu-scan' benchmark: Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 546.987 usec (+- 0.553 usec) Average PMU scanning took: 1562.814 usec (+- 22.729 usec) Performance counter stats for 'perf bench internals pmu-scan -i1000' (5 runs): 3170.86 msec task-clock:u # 0.992 CPUs utilized ( +- 0.22% ) 0 context-switches:u # 0.000 /sec 0 cpu-migrations:u # 0.000 /sec 1010 page-faults:u # 318.526 /sec ( +- 0.04% ) 11890047674 cycles:u # 3.750 GHz ( +- 0.14% ) (83.27%) 119090499 stalled-cycles-frontend:u # 1.00% frontend cycles idle ( +- 0.46% ) (83.40%) 32502449 stalled-cycles-backend:u # 0.27% backend cycles idle ( +- 8.32% ) (83.30%) 33119141261 instructions:u # 2.79 insn per cycle # 0.00 stalled cycles per insn ( +- 0.01% ) (83.37%) 6812816561 branches:u # 2.149 G/sec ( +- 0.01% ) (83.29%) 70157855 branch-misses:u # 1.03% of all branches ( +- 0.28% ) (83.38%) 3.19710 +- 0.00826 seconds time elapsed ( +- 0.26% ) $ Signed-off-by:Ian Rogers <irogers@google.com> Tested-by:
Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Gaosheng Cui <cuigaosheng1@huawei.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Clark <james.clark@arm.com> Cc: Jing Zhang <renyu.zj@linux.alibaba.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: John Garry <john.g.garry@oracle.com> Cc: Kajol Jain <kjain@linux.ibm.com> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Cc: Rob Herring <robh@kernel.org> Link: https://lore.kernel.org/r/20230824041330.266337-2-irogers@google.comSigned-off-by:
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