lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

perf stat: Add stalled cycles to the default output

Browse Source 
The new default output looks like this:

 Performance counter stats for './loop_1b_instructions':

        236.010686 task-clock               #    0.996 CPUs utilized
                 0 context-switches         #    0.000 M/sec
                 0 CPU-migrations           #    0.000 M/sec
                99 page-faults              #    0.000 M/sec
       756,487,646 cycles                   #    3.205 GHz
       354,938,996 stalled-cycles           #   46.92% of all cycles are idle
     1,001,403,797 instructions             #    1.32  insns per cycle
                                            #    0.35  stalled cycles per insn
       100,279,773 branches                 #  424.895 M/sec
            12,646 branch-misses            #    0.013 % of all branches

        0.236902540  seconds time elapsed

We dropped cache-refs and cache-misses and added stalled-cycles - this is a
more generic "how well utilized is the CPU" metric.

If the stalled-cycles ratio is too high then more specific measurements can be
taken to figure out the source of the inefficiency.

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-pbpl2l4mn797s69bclfpwkwn@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar
2011-04-27 05:20:22 +02:00
parent 481f988a01
commit 1fc570ad89
2 changed files with 8 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
tools/perf/builtin-stat.c
View File

@@ -65,11 +65,10 @@ static struct perf_event_attr default_attrs[] = {
{ .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_PAGE_FAULTS },
{ .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_CPU_CYCLES },
{ .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES },
{ .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_INSTRUCTIONS },
{ .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS },
{ .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_BRANCH_MISSES },
{ .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_CACHE_REFERENCES },
{ .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_CACHE_MISSES },
};
@@ -468,7 +467,7 @@ static void abs_printout(int cpu, struct perf_evsel *evsel, double avg)
if (total)
ratio = avg * 100 / total;
fprintf(stderr, " # %8.3f %% of all branches", ratio);
fprintf(stderr, " # %5.2f %% of all branches ", ratio);
} else if (perf_evsel__match(evsel, HARDWARE, HW_CACHE_MISSES) &&
runtime_cacherefs_stats[cpu].n != 0) {