From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752153Ab3LBAB7 (ORCPT ); Sun, 1 Dec 2013 19:01:59 -0500 Received: from mail-pd0-f179.google.com ([209.85.192.179]:36240 "EHLO mail-pd0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751412Ab3LBABz (ORCPT ); Sun, 1 Dec 2013 19:01:55 -0500 From: David Ahern To: acme@ghostprotocols.net, linux-kernel@vger.kernel.org Cc: David Ahern , Jiri Olsa Subject: [PATCH] perf tool: Ensure forward progress unwinding frames Date: Sun, 1 Dec 2013 17:01:49 -0700 Message-Id: <1385942509-11445-1-git-send-email-dsahern@gmail.com> X-Mailer: git-send-email 1.8.3.4 (Apple Git-47) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: Jiri Olsa --- 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)