lkml.org 
[lkml]   [2013]   [Dec]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] perf tool: Ensure forward progress unwinding frames
Date
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 <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@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)


\
 
 \ /
  Last update: 2013-12-02 01:21    [W:0.120 / U:0.120 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site