The dwarf option for callstacks is getting stuck on the unwind and showing
repeated frames. For example,
qemu-system-x86 13759 [001] 287663.084957: syscalls:sys_enter_futex: uaddr:
0x7f770a958700, op: 0x00000081, val: 0x00000001, utime: 0x7f75ea
7f7705fd23ea __lll_unlock_wake (/lib64/libpthread-2.14.90.so)
7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so)
7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so)
7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so)
7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so)
7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so)
...
(Last frame repeats 126 times)
Catch that the same frame is hit multiple times and break out of the loop.
With this patch:
qemu-system-x86 13759 [001] 287663.084967: syscalls:sys_exit_futex: 0x1
7f7705fd23ea __lll_unlock_wake (/lib64/libpthread-2.14.90.so)
7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so)
Signed-off-by: David Ahern <dsah...@gmail.com>
Cc: Jiri Olsa <jo...@redhat.com>
---
tools/perf/util/unwind.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/tools/perf/util/unwind.c b/tools/perf/util/unwind.c
index 0efd5393de85..817ffc1f3a00 100644
--- a/tools/perf/util/unwind.c
+++ b/tools/perf/util/unwind.c
@@ -563,6 +563,7 @@ static int get_entries(struct unwind_info *ui,
unwind_entry_cb_t cb,
{
unw_addr_space_t addr_space;
unw_cursor_t c;
+ unw_word_t prev_ip = 0;
int ret;
addr_space = unw_create_addr_space(&accessors, 0);
@@ -579,6 +580,10 @@ static int get_entries(struct unwind_info *ui,
unwind_entry_cb_t cb,
unw_word_t ip;
unw_get_reg(&c, UNW_REG_IP, &ip);
+ if (ip == prev_ip)
+ break;
+ prev_ip = ip;
+
ret = entry(ip, ui->thread, ui->machine, cb, arg);
}
--
1.8.3.4 (Apple Git-47)
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