On 12/9/13, 3:02 AM, Jiri Olsa wrote:
On 12/1/13, 5:01 PM, David Ahern wrote:
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)
...
I wonder this is us or libunwind bug (or cfi code) ;-)
looks like you can reproduce..? are you using the latest libunwind?
$ rpm -q libunwind
libunwind-0.99-2.20110424git1e10c293.fc16.x86_64
(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 <[email protected]>
Cc: Jiri Olsa <[email protected]>
---
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;
hum, how about recursion?
how about some counter and break after some insane value
I chose > 1 as the insane value. Do you have a suggestion on something
else? 5? 10?
and maybe display some warning..
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)
warning: unwind broken
sure.
David
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