perf diff: Percent calcs should use double values
Otherwise we do integer math and the delta values round up to
multiples of 1.0%.
Also, calculate absolute values. Things look precise now:
$ perf report -i perf.data.old --sort dso,symbol | head -13
9.02% libc-2.10.1.so [.] _IO_vfprintf_internal
4.88% find [.] 0x00000000014af0
2.91% [kernel] [k] __kmalloc
2.85% [kernel] [k] ext4_htree_store_dirent
2.50% libc-2.10.1.so [.] __GI_memmove
2.44% [kernel] [k] half_md4_transform
2.43% [kernel] [k] _spin_lock
2.33% [kernel] [k] system_call
$ perf report -i perf.data --sort dso,symbol | head -13
8.55% libc-2.10.1.so [.] _IO_vfprintf_internal
3.11% [kernel] [k] __kmalloc
3.07% [kernel] [k] ext4_htree_store_dirent
2.66% find [.] 0x00000000016bcf
2.61% [kernel] [k] _atomic_dec_and_lock
2.46% [kernel] [k] half_md4_transform
2.41% libc-2.10.1.so [.] __GI_memmove
2.30% find [.] 0x00000000009219
$ perf diff | head -13
9.02% -0.47% libc-2.10.1.so [.] _IO_vfprintf_internal
2.91% +0.20% [kernel] [k] __kmalloc
2.85% +0.23% [kernel] [k] ext4_htree_store_dirent
1.99% +0.62% [kernel] [k] _atomic_dec_and_lock
2.44% +0.02% [kernel] [k] half_md4_transform
2.50% -0.09% libc-2.10.1.so [.] __GI_memmove
1.88% +0.01% [kernel] [k] __d_lookup
2.43% -0.75% [kernel] [k] _spin_lock
0.97% +0.62% [kernel] [k] path_get
1.99% -0.42% libc-2.10.1.so [.] _int_malloc
$
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1260981109-2621-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index ecf853c..e8daf5c 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -1,6 +1,7 @@
#include "hist.h"
#include "session.h"
#include "sort.h"
+#include <math.h>
struct callchain_param callchain_param = {
.mode = CHAIN_GRAPH_REL,
@@ -494,13 +495,13 @@
double old_percent = 0, new_percent = 0, diff;
if (total > 0)
- old_percent = (count * 100) / total;
+ old_percent = (count * 100.0) / total;
if (session->events_stats.total > 0)
- new_percent = (self->count * 100) / session->events_stats.total;
+ new_percent = (self->count * 100.0) / session->events_stats.total;
- diff = old_percent - new_percent;
+ diff = new_percent - old_percent;
- if ((u64)diff != 0)
+ if (fabs(diff) >= 0.01)
snprintf(bf, sizeof(bf), "%+4.2F%%", diff);
else
snprintf(bf, sizeof(bf), " ");