ping.. Jiri, any thoughts on this? 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) ... (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; + ret = entry(ip, ui->thread, ui->machine, cb, arg); }
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