perf stat VERSUS perf stat report :: TopDown Metrics

[Michael Petlan <mpetlan@redhat.com>]

Hello!

I have a test for perf-stat record/report functionality, which compares the outputs,
basically whether `perf stat report` is able to reconstruct the same results as
printed by `perf stat`. In the Intel environments with TopDown events/metrics, the
test started failing on the fact that perf-stat-report has a different approach to
handle the metrics:

================================ perf stat ================================
 Performance counter stats for 'ls':

              0.69 msec task-clock                   #    0.477 CPUs utilized
                 0      context-switches             #    0.000 /sec
                 0      cpu-migrations               #    0.000 /sec
                97      page-faults                  #  139.648 K/sec
         1,776,212      cycles                       #    2.557 GHz
         1,970,435      instructions                 #    1.11  insn per cycle
           403,140      branches                     #  580.389 M/sec
            11,837      branch-misses                #    2.94% of all branches
                        TopdownL1             #     30.0 %  tma_backend_bound
                                              #     13.0 %  tma_bad_speculation
                                              #     37.5 %  tma_frontend_bound
                                              #     19.5 %  tma_retiring
                        TopdownL2             #     12.1 %  tma_branch_mispredicts
                                              #     11.7 %  tma_core_bound
                                              #     13.2 %  tma_fetch_bandwidth
                                              #     24.3 %  tma_fetch_latency
                                              #      3.1 %  tma_heavy_operations
                                              #     16.3 %  tma_light_operations
                                              #      1.0 %  tma_machine_clears
                                              #     18.3 %  tma_memory_bound

       0.001456908 seconds time elapsed

       0.000000000 seconds user
       0.001647000 seconds sys

================================ perf stat report ================================
 Performance counter stats for '/usr/bin/perf stat record ls':

              0.69 msec task-clock                   #    0.477 CPUs utilized
                 0      context-switches             #    0.000 /sec
                 0      cpu-migrations               #    0.000 /sec
                97      page-faults                  #  139.648 K/sec
         1,776,212      cycles                       #    2.557 GHz
         1,970,435      instructions                 #    1.11  insn per cycle
           403,140      branches                     #  580.389 M/sec
            11,837      branch-misses                #    2.94% of all branches
        10,657,272      TOPDOWN.SLOTS
         2,089,661      topdown-retiring
         4,053,942      topdown-fe-bound
         1,964,281      topdown-mem-bound
         3,218,078      topdown-be-bound
           334,345      topdown-heavy-ops
         1,295,589      topdown-br-mispredict
         2,632,973      topdown-fetch-lat
         1,379,176      topdown-bad-spec
            21,248      INT_MISC.UOP_DROPPING        #   30.590 M/sec

       0.001456908 seconds time elapsed

While perf-stat (and perf-stat-record) calculates the percentages, perf-stat-report
just prints the raw numbers. Thinking about it, it might be useful to know the raw
numbers too, but rather via an option, while by default, both should behave the same,
shouldn't they? Is perf-stat-report missing some metric postprocessing?

Thanks!

Michael