perf tests: Do not rely on dso__data_read_offset() to open dso

Do not rely on dso__data_read_offset() will always call dso__data_fd()
internally.  With multi-thread support, accessing a fd will be protected
by a lock and it'll cause a huge contention.  It can be avoided since we
can skip reading from file if there's a data in the dso cache.

If one needs to call the dso__data_read_offset(), [s]he also needs to
call dso__data_fd() (or set dso->binary_type at least) first like the
dwarf unwind code does.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1422585209-32742-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/tests/dso-data.c b/tools/perf/tests/dso-data.c
index 22a8c428283ab820ff0dec4d8e8d7952664db8b8..513e5febbe5a5016ed5d9a2564bea1e5bc92e4e8 100644 (file)
--- a/tools/perf/tests/dso-data.c
+++ b/tools/perf/tests/dso-data.c
@@ -112,6 +112,9 @@ int test__dso_data(void)
 
        dso = dso__new((const char *)file);
 
+       TEST_ASSERT_VAL("Failed to access to dso",
+                       dso__data_fd(dso, &machine) >= 0);
+
        /* Basic 10 bytes tests. */
        for (i = 0; i < ARRAY_SIZE(offsets); i++) {
                struct test_data_offset *data = &offsets[i];
@@ -252,13 +255,13 @@ int test__dso_data_cache(void)
                struct dso *dso = dsos[i];
 
                /*
-                * Open dsos via dso__data_fd or dso__data_read_offset.
-                * Both opens the data file and keep it open.
+                * Open dsos via dso__data_fd(), it opens the data
+                * file and keep it open (unless open file limit).
                 */
+               fd = dso__data_fd(dso, &machine);
+               TEST_ASSERT_VAL("failed to get fd", fd > 0);
+
                if (i % 2) {
-                       fd = dso__data_fd(dso, &machine);
-                       TEST_ASSERT_VAL("failed to get fd", fd > 0);
-               } else {
                        #define BUFSIZE 10
                        u8 buf[BUFSIZE];
                        ssize_t n;