[PATCH v2 0/3] perf annotate: Bugfixes

[PATCH v2 0/3] perf annotate: Bugfixes

[Taeung Song]

Hi,

perf-annotate has little bugs so I fix them.
I'd appreciate some feedback on this patchset. :)

Thanks,
Taeung

v2:
- more clearly commit log messages (Arnaldo)
- rebased on current acme/perf/core

Taeung Song (3):
  perf annotate: Fix a bug reading link name from a build-id file
  perf annotate: Fix a bug of division by zero when calculating percent
  perf annotate: Fix missing number of samples

 tools/perf/util/annotate.c | 24 +++++++++++++++++++-----
 tools/perf/util/annotate.h |  2 +-
 2 files changed, 20 insertions(+), 6 deletions(-)

-- 
2.7.4

[PATCH v2 1/3] perf annotate: Fix a bug reading link name from a build-id file

[Taeung Song]

It is wrong way to read link name from a build-id file.
Because a build-id file is not symbolic link
but build-id directory of it is symbolic link, so fix it.

For example, if build-id file name gotten from
dso__build_id_filename() is as below,

  /root/.debug/.build-id/4f/75c7d197c951659d1c1b8b5fd49bcdf8f3f8b1/elf

To correctly read link name of build-id,
use the build-id dir path that is a symbolic link,
instead of the above build-id file name like below.

  /root/.debug/.build-id/4f/75c7d197c951659d1c1b8b5fd49bcdf8f3f8b1

Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
---
 tools/perf/util/annotate.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 22cd1db..20de715 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1307,6 +1307,7 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
 {
 	char linkname[PATH_MAX];
 	char *build_id_filename;
+	char *build_id_path = NULL;
 
 	if (dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
 	    !dso__is_kcore(dso))
@@ -1322,8 +1323,14 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
 		goto fallback;
 	}
 
+	build_id_path = strdup(filename);
+	if (!build_id_path)
+		return -1;
+
+	dirname(build_id_path);
+
 	if (dso__is_kcore(dso) ||
-	    readlink(filename, linkname, sizeof(linkname)) < 0 ||
+	    readlink(build_id_path, linkname, sizeof(linkname)) < 0 ||
 	    strstr(linkname, DSO__NAME_KALLSYMS) ||
 	    access(filename, R_OK)) {
 fallback:
@@ -1335,6 +1342,7 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
 		__symbol__join_symfs(filename, filename_size, dso->long_name);
 	}
 
+	free(build_id_path);
 	return 0;
 }
 
-- 
2.7.4

[PATCH v2 2/3] perf annotate: Fix a bug of division by zero when calculating percent

[Taeung Song]

Currently perf-annotate with --print-line can print
-nan(0x8000000000000) because of division by zero
when calculating percent. The division by zero happen
when a sum of samples is zero in symbol__get_source_line(),
so fix it.

For examples,
After running 'perf record' like below,

    $ perf record -e "{cycles,page-faults,branch-misses}" ./a.out

Before:

    $ perf annotate --stdio -l

Sorted summary for file /home/taeung/workspace/a.out
----------------------------------------------

   32.89    -nan    7.04 a.c:38
   25.14    -nan    0.00 a.c:34
   16.26    -nan   56.34 a.c:31
   15.88    -nan    1.41 a.c:37
    5.67    -nan    0.00 a.c:39
    1.13    -nan   35.21 a.c:26
    0.95    -nan    0.00 a.c:44
    0.57    -nan    0.00 a.c:32
 Percent                 |      Source code & Disassembly of a.out for cycles (529 samples)
-----------------------------------------------------------------------------------------
                         :
...

 a.c:26    0.57    -nan    4.23 :         40081a:       mov    %edi,-0x24(%rbp)
 a.c:26    0.00    -nan    9.86 :         40081d:       mov    %rsi,-0x30(%rbp)

...

However, if a sum of samples is zero (e.g. 'page-faults'),
skip calculating percent.

After:

    $ perf annotate --stdio -l

Sorted summary for file /home/taeung/workspace/a.out
----------------------------------------------

   32.89    0.00    7.04 a.c:38
   25.14    0.00    0.00 a.c:34
   16.26    0.00   56.34 a.c:31
   15.88    0.00    1.41 a.c:37
    5.67    0.00    0.00 a.c:39
    1.13    0.00   35.21 a.c:26
    0.95    0.00    0.00 a.c:44
    0.57    0.00    0.00 a.c:32
 Percent                 |      Source code & Disassembly of old for cycles (529 samples)
-----------------------------------------------------------------------------------------
                         :
...

a.c:26    0.57    0.00    4.23 :         40081a:       mov    %edi,-0x24(%rbp)
a.c:26    0.00    0.00    9.86 :         40081d:       mov    %rsi,-0x30(%rbp)

...

Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
---
 tools/perf/util/annotate.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 20de715..db3ebf1 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1671,11 +1671,15 @@ static int symbol__get_source_line(struct symbol *sym, struct map *map,
 		src_line->nr_pcnt = nr_pcnt;
 
 		for (k = 0; k < nr_pcnt; k++) {
+			double percent = 0.0;
+
 			h = annotation__histogram(notes, evidx + k);
-			src_line->samples[k].percent = 100.0 * h->addr[i] / h->sum;
+			if (h->sum)
+				percent = 100.0 * h->addr[i] / h->sum;
 
-			if (src_line->samples[k].percent > percent_max)
-				percent_max = src_line->samples[k].percent;
+			if (percent > percent_max)
+				percent_max = percent;
+			src_line->samples[k].percent = percent;
 		}
 
 		if (percent_max <= 0.5)
-- 
2.7.4

[PATCH v2 3/3] perf annotate: Fix missing number of samples

[Taeung Song]

If running 'perf annotate --stdio -l --show-total-period',
you can see a problem showing only zero '0' for number of samples.

Before:
    $ perf annotate --stdio -l --show-total-period
...
       0 :        400816:       push   %rbp
       0 :        400817:       mov    %rsp,%rbp
       0 :        40081a:       mov    %edi,-0x24(%rbp)
       0 :        40081d:       mov    %rsi,-0x30(%rbp)
       0 :        400821:       mov    -0x24(%rbp),%eax
       0 :        400824:       mov    -0x30(%rbp),%rdx
       0 :        400828:       mov    (%rdx),%esi
       0 :        40082a:       mov    $0x0,%edx
...

The reason is number of samples aren't set
in symbol__get_source_line(). so set it ordinarily.

After:
    $ perf annotate --stdio -l --show-total-period
...
       3 :        400816:       push   %rbp
       4 :        400817:       mov    %rsp,%rbp
       0 :        40081a:       mov    %edi,-0x24(%rbp)
       0 :        40081d:       mov    %rsi,-0x30(%rbp)
       1 :        400821:       mov    -0x24(%rbp),%eax
       2 :        400824:       mov    -0x30(%rbp),%rdx
       0 :        400828:       mov    (%rdx),%esi
       1 :        40082a:       mov    $0x0,%edx
...

Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
---
 tools/perf/util/annotate.c | 6 ++++--
 tools/perf/util/annotate.h | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index db3ebf1..23f36cb 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1665,7 +1665,7 @@ static int symbol__get_source_line(struct symbol *sym, struct map *map,
 	start = map__rip_2objdump(map, sym->start);
 
 	for (i = 0; i < len; i++) {
-		u64 offset;
+		u64 offset, nr_samples;
 		double percent_max = 0.0;
 
 		src_line->nr_pcnt = nr_pcnt;
@@ -1674,12 +1674,14 @@ static int symbol__get_source_line(struct symbol *sym, struct map *map,
 			double percent = 0.0;
 
 			h = annotation__histogram(notes, evidx + k);
+			nr_samples = h->addr[i];
 			if (h->sum)
-				percent = 100.0 * h->addr[i] / h->sum;
+				percent = 100.0 * nr_samples / h->sum;
 
 			if (percent > percent_max)
 				percent_max = percent;
 			src_line->samples[k].percent = percent;
+			src_line->samples[k].nr = nr_samples;
 		}
 
 		if (percent_max <= 0.5)
diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h
index 09776b5..948aa8e 100644
--- a/tools/perf/util/annotate.h
+++ b/tools/perf/util/annotate.h
@@ -98,7 +98,7 @@ struct cyc_hist {
 struct source_line_samples {
 	double		percent;
 	double		percent_sum;
-	double          nr;
+	u64		nr;
 };
 
 struct source_line {
-- 
2.7.4