From: Peter Zijlstra on
Use the PERF_RECORD_MISC_EXACT information to measure the success
rate of the PEBS fix-up.

Signed-off-by: Peter Zijlstra <a.p.zijlstra(a)chello.nl>
LKML-Reference: <new-submission>
---
tools/perf/builtin-top.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

Index: linux-2.6/tools/perf/builtin-top.c
===================================================================
--- linux-2.6.orig/tools/perf/builtin-top.c
+++ linux-2.6/tools/perf/builtin-top.c
@@ -410,6 +410,7 @@ static double sym_weight(const struct sy

static long samples;
static long userspace_samples;
+static long exact_samples;
static const char CONSOLE_CLEAR[] = "";

static void __list_insert_active_sym(struct sym_entry *syme)
@@ -450,6 +451,7 @@ static void print_sym_table(void)
int counter, snap = !display_weighted ? sym_counter : 0;
float samples_per_sec = samples/delay_secs;
float ksamples_per_sec = (samples-userspace_samples)/delay_secs;
+ float esamples_percent = (100.0*exact_samples)/samples;
float sum_ksamples = 0.0;
struct sym_entry *syme, *n;
struct rb_root tmp = RB_ROOT;
@@ -457,7 +459,7 @@ static void print_sym_table(void)
int sym_width = 0, dso_width = 0, max_dso_width;
const int win_width = winsize.ws_col - 1;

- samples = userspace_samples = 0;
+ samples = userspace_samples = exact_samples = 0;

/* Sort the active symbols */
pthread_mutex_lock(&active_symbols_lock);
@@ -488,9 +490,10 @@ static void print_sym_table(void)
puts(CONSOLE_CLEAR);

printf("%-*.*s\n", win_width, win_width, graph_dotted_line);
- printf( " PerfTop:%8.0f irqs/sec kernel:%4.1f%% [",
+ printf( " PerfTop:%8.0f irqs/sec kernel:%4.1f%% exact: %4.1f%% [",
samples_per_sec,
- 100.0 - (100.0*((samples_per_sec-ksamples_per_sec)/samples_per_sec)));
+ 100.0 - (100.0*((samples_per_sec-ksamples_per_sec)/samples_per_sec)),
+ esamples_percent);

if (nr_counters == 1 || !display_weighted) {
printf("%Ld", (u64)attrs[0].sample_period);
@@ -954,6 +957,9 @@ static void event__process_sample(const
return;
}

+ if (self->header.misc & PERF_RECORD_MISC_EXACT)
+ exact_samples++;
+
if (event__preprocess_sample(self, session, &al, symbol_filter) < 0 ||
al.filtered)
return;

--

--
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