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perf stat: Analyze front-end and back-end stall counts 

Sample output:

 Performance counter stats for './loop_1b':

        873.691065 task-clock               #    1.000 CPUs utilized
                 1 context-switches         #    0.000 M/sec
                 1 CPU-migrations           #    0.000 M/sec
                96 page-faults              #    0.000 M/sec
     2,012,637,222 cycles                   #    2.304 GHz                      (66.58%)
     1,001,397,911 stalled-cycles-frontend  #   49.76% frontend cycles idle     (66.58%)
         7,523,398 stalled-cycles-backend   #    0.37%  backend cycles idle     (66.76%)
     2,004,551,046 instructions             #    1.00  insns per cycle
                                            #    0.50  stalled cycles per insn  (66.80%)
     1,001,304,992 branches                 # 1146.063 M/sec                    (66.76%)
            39,453 branch-misses            #    0.00% of all branches          (66.64%)

        0.874046121  seconds time elapsed

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-7y40wib8n003io7hjpn1dsrm@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2011-04-29 13:49:08 +02:00
parent 129c04cb8c
commit d3d1e86da0
2 changed files with 39 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
tools/perf/builtin-stat.c
View File

@ -201,7 +201,8 @@ static double stddev_stats(struct stats *stats)
struct stats runtime_nsecs_stats[MAX_NR_CPUS];
struct stats runtime_cycles_stats[MAX_NR_CPUS];
struct stats runtime_stalled_cycles_stats[MAX_NR_CPUS];
struct stats runtime_stalled_cycles_front_stats[MAX_NR_CPUS];
struct stats runtime_stalled_cycles_back_stats[MAX_NR_CPUS];
struct stats runtime_branches_stats[MAX_NR_CPUS];
struct stats runtime_cacherefs_stats[MAX_NR_CPUS];
struct stats runtime_l1_dcache_stats[MAX_NR_CPUS];
@ -251,8 +252,10 @@ static void update_shadow_stats(struct perf_evsel *counter, u64 *count)
update_stats(&runtime_nsecs_stats[0], count[0]);
else if (perf_evsel__match(counter, HARDWARE, HW_CPU_CYCLES))
update_stats(&runtime_cycles_stats[0], count[0]);
else if (perf_evsel__match(counter, HARDWARE, HW_STALLED_CYCLES_FRONTEND))
update_stats(&runtime_stalled_cycles_front_stats[0], count[0]);
else if (perf_evsel__match(counter, HARDWARE, HW_STALLED_CYCLES_BACKEND))
update_stats(&runtime_stalled_cycles_stats[0], count[0]);
update_stats(&runtime_stalled_cycles_back_stats[0], count[0]);
else if (perf_evsel__match(counter, HARDWARE, HW_BRANCH_INSTRUCTIONS))
update_stats(&runtime_branches_stats[0], count[0]);
else if (perf_evsel__match(counter, HARDWARE, HW_CACHE_REFERENCES))
@ -478,7 +481,30 @@ static void nsec_printout(int cpu, struct perf_evsel *evsel, double avg)
fprintf(stderr, " # %8.3f CPUs utilized ", avg / avg_stats(&walltime_nsecs_stats));
}
static void print_stalled_cycles(int cpu, struct perf_evsel *evsel __used, double avg)
static void print_stalled_cycles_frontend(int cpu, struct perf_evsel *evsel __used, double avg)
{
double total, ratio = 0.0;
const char *color;
total = avg_stats(&runtime_cycles_stats[cpu]);
if (total)
ratio = avg / total * 100.0;
color = PERF_COLOR_NORMAL;
if (ratio > 75.0)
color = PERF_COLOR_RED;
else if (ratio > 50.0)
color = PERF_COLOR_MAGENTA;
else if (ratio > 20.0)
color = PERF_COLOR_YELLOW;
fprintf(stderr, " # ");
color_fprintf(stderr, color, "%5.2f%%", ratio);
fprintf(stderr, " frontend cycles idle ");
}
static void print_stalled_cycles_backend(int cpu, struct perf_evsel *evsel __used, double avg)
{
double total, ratio = 0.0;
const char *color;
@ -498,7 +524,7 @@ static void print_stalled_cycles(int cpu, struct perf_evsel *evsel __used, doubl
fprintf(stderr, " # ");
color_fprintf(stderr, color, "%5.2f%%", ratio);
fprintf(stderr, " of all cycles are idle ");
fprintf(stderr, " backend cycles idle ");
}
static void print_branch_misses(int cpu, struct perf_evsel *evsel __used, double avg)
@ -583,7 +609,8 @@ static void abs_printout(int cpu, struct perf_evsel *evsel, double avg)
fprintf(stderr, " # %4.2f insns per cycle ", ratio);
total = avg_stats(&runtime_stalled_cycles_stats[cpu]);
total = avg_stats(&runtime_stalled_cycles_front_stats[cpu]);
total = max(total, avg_stats(&runtime_stalled_cycles_back_stats[cpu]));
if (total && avg) {
ratio = total / avg;
@ -609,8 +636,10 @@ static void abs_printout(int cpu, struct perf_evsel *evsel, double avg)
fprintf(stderr, " # %8.3f %% of all cache refs ", ratio);
} else if (perf_evsel__match(evsel, HARDWARE, HW_STALLED_CYCLES_FRONTEND)) {
print_stalled_cycles_frontend(cpu, evsel, avg);
} else if (perf_evsel__match(evsel, HARDWARE, HW_STALLED_CYCLES_BACKEND)) {
print_stalled_cycles(cpu, evsel, avg);
print_stalled_cycles_backend(cpu, evsel, avg);
} else if (perf_evsel__match(evsel, HARDWARE, HW_CPU_CYCLES)) {
total = avg_stats(&runtime_nsecs_stats[cpu]);

7
tools/perf/util/parse-events.c
View File

@ -60,7 +60,7 @@ static struct event_symbol event_symbols[] = {
#define PERF_EVENT_TYPE(config) __PERF_EVENT_FIELD(config, TYPE)
#define PERF_EVENT_ID(config) __PERF_EVENT_FIELD(config, EVENT)
static const char *hw_event_names[] = {
static const char *hw_event_names[PERF_COUNT_HW_MAX] = {
"cycles",
"instructions",
"cache-references",
@ -68,10 +68,11 @@ static const char *hw_event_names[] = {
"branches",
"branch-misses",
"bus-cycles",
"stalled-cycles",
"stalled-cycles-frontend",
"stalled-cycles-backend",
};
static const char *sw_event_names[] = {
static const char *sw_event_names[PERF_COUNT_SW_MAX] = {
"cpu-clock",
"task-clock",
"page-faults",