[PATCH] perf report: Fix wrong iteration count
From: Jin Yao
Date: Fri Jan 04 2019 - 01:12:04 EST
By calculating the removed loops, we can get the iteration count.
But the iteration count could be reported incorrectly, reporting
impossibly high counts. That's because previous code uses the
number of removed LBR entries for the iteration count. That's
not good. Fix this by increasing the iteration count when a loop
is detected.
When matching the chain, the iteration count would be added up,
finally we need to compute the average value when printing out.
For example,
perf report --branch-history --stdio --no-children
Before:
---f2 +0
|
|--33.62%--f1 +9 (cycles:1)
| f1 +0
| main +22 (cycles:1)
| main +17
| main +38 (cycles:1)
| main +27
| f1 +26 (cycles:1)
| f1 +24
| f2 +27 (cycles:7)
| f2 +0
| f1 +19 (cycles:1)
| f1 +14
| f2 +27 (cycles:11)
| f2 +0
| f1 +9 (cycles:1 iter:2968 avg_cycles:3)
| f1 +0
| main +22 (cycles:1 iter:2968 avg_cycles:3)
| main +17
| main +38 (cycles:1 iter:2968 avg_cycles:3)
2968 is an impossible high iteration count and avg_cycles is too small.
After:
---f2 +0
|
|--33.62%--f1 +9 (cycles:1)
| f1 +0
| main +22 (cycles:1)
| main +17
| main +38 (cycles:1)
| main +27
| f1 +26 (cycles:1)
| f1 +24
| f2 +27 (cycles:7)
| f2 +0
| f1 +19 (cycles:1)
| f1 +14
| f2 +27 (cycles:11)
| f2 +0
| f1 +9 (cycles:1 iter:1 avg_cycles:23)
| f1 +0
| main +22 (cycles:1 iter:1 avg_cycles:23)
| main +17
| main +38 (cycles:1 iter:1 avg_cycles:23)
avg_cycles:23 is the average cycles of this iteration.
Fixes: c4ee06251d42 ("perf report: Calculate the average cycles of iterations")
Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
---
tools/perf/util/callchain.c | 32 ++++++++++++++++++++------------
tools/perf/util/callchain.h | 1 +
tools/perf/util/machine.c | 2 +-
3 files changed, 22 insertions(+), 13 deletions(-)
diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 32ef7bd..dc2212e 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -766,6 +766,7 @@ static enum match_result match_chain(struct callchain_cursor_node *node,
cnode->cycles_count += node->branch_flags.cycles;
cnode->iter_count += node->nr_loop_iter;
cnode->iter_cycles += node->iter_cycles;
+ cnode->from_count++;
}
}
@@ -1345,10 +1346,10 @@ static int branch_to_str(char *bf, int bfsize,
static int branch_from_str(char *bf, int bfsize,
u64 branch_count,
u64 cycles_count, u64 iter_count,
- u64 iter_cycles)
+ u64 iter_cycles, u64 from_count)
{
int printed = 0, i = 0;
- u64 cycles;
+ u64 cycles, v = 0;
cycles = cycles_count / branch_count;
if (cycles) {
@@ -1357,14 +1358,16 @@ static int branch_from_str(char *bf, int bfsize,
bf + printed, bfsize - printed);
}
- if (iter_count) {
- printed += count_pri64_printf(i++, "iter",
- iter_count,
- bf + printed, bfsize - printed);
+ if (iter_count && from_count) {
+ v = iter_count / from_count;
+ if (v) {
+ printed += count_pri64_printf(i++, "iter",
+ v, bf + printed, bfsize - printed);
- printed += count_pri64_printf(i++, "avg_cycles",
- iter_cycles / iter_count,
- bf + printed, bfsize - printed);
+ printed += count_pri64_printf(i++, "avg_cycles",
+ iter_cycles / iter_count,
+ bf + printed, bfsize - printed);
+ }
}
if (i)
@@ -1377,6 +1380,7 @@ static int counts_str_build(char *bf, int bfsize,
u64 branch_count, u64 predicted_count,
u64 abort_count, u64 cycles_count,
u64 iter_count, u64 iter_cycles,
+ u64 from_count,
struct branch_type_stat *brtype_stat)
{
int printed;
@@ -1389,7 +1393,8 @@ static int counts_str_build(char *bf, int bfsize,
predicted_count, abort_count, brtype_stat);
} else {
printed = branch_from_str(bf, bfsize, branch_count,
- cycles_count, iter_count, iter_cycles);
+ cycles_count, iter_count, iter_cycles,
+ from_count);
}
if (!printed)
@@ -1402,13 +1407,14 @@ static int callchain_counts_printf(FILE *fp, char *bf, int bfsize,
u64 branch_count, u64 predicted_count,
u64 abort_count, u64 cycles_count,
u64 iter_count, u64 iter_cycles,
+ u64 from_count,
struct branch_type_stat *brtype_stat)
{
char str[256];
counts_str_build(str, sizeof(str), branch_count,
predicted_count, abort_count, cycles_count,
- iter_count, iter_cycles, brtype_stat);
+ iter_count, iter_cycles, from_count, brtype_stat);
if (fp)
return fprintf(fp, "%s", str);
@@ -1422,6 +1428,7 @@ int callchain_list_counts__printf_value(struct callchain_list *clist,
u64 branch_count, predicted_count;
u64 abort_count, cycles_count;
u64 iter_count, iter_cycles;
+ u64 from_count;
branch_count = clist->branch_count;
predicted_count = clist->predicted_count;
@@ -1429,11 +1436,12 @@ int callchain_list_counts__printf_value(struct callchain_list *clist,
cycles_count = clist->cycles_count;
iter_count = clist->iter_count;
iter_cycles = clist->iter_cycles;
+ from_count = clist->from_count;
return callchain_counts_printf(fp, bf, bfsize, branch_count,
predicted_count, abort_count,
cycles_count, iter_count, iter_cycles,
- &clist->brtype_stat);
+ from_count, &clist->brtype_stat);
}
static void free_callchain_node(struct callchain_node *node)
diff --git a/tools/perf/util/callchain.h b/tools/perf/util/callchain.h
index 154560b..99d38ac 100644
--- a/tools/perf/util/callchain.h
+++ b/tools/perf/util/callchain.h
@@ -118,6 +118,7 @@ struct callchain_list {
bool has_children;
};
u64 branch_count;
+ u64 from_count;
u64 predicted_count;
u64 abort_count;
u64 cycles_count;
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 6fcb3bc..143f705 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2005,7 +2005,7 @@ static void save_iterations(struct iterations *iter,
{
int i;
- iter->nr_loop_iter = nr;
+ iter->nr_loop_iter++;
iter->cycles = 0;
for (i = 0; i < nr; i++)
--
2.7.4