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authorFrederic Weisbecker <fweisbec@gmail.com>2008-11-17 03:22:41 +0100
committerIngo Molnar <mingo@elte.hu>2008-11-18 11:11:00 +0100
commit0231022cc32d5f2e7f3c06b75691dda0ad6aec33 (patch)
treeb45429e95fc7d52bae32e62ef514f3d7ccf62ce6 /include
parent0619faf657806b943e6acf51f60f1cd023a96c78 (diff)
tracing/function-return-tracer: add the overrun field
Impact: help to find the better depth of trace We decided to arbitrary define the depth of function return trace as "20". Perhaps this is not enough. To help finding an optimal depth, we measure now the overrun: the number of functions that have been missed for the current thread. By default this is not displayed, we have to do set a particular flag on the return tracer: echo overrun > /debug/tracing/trace_options And the overrun will be printed on the right. As the trace shows below, the current 20 depth is not enough. update_wall_time+0x37f/0x8c0 -> update_xtime_cache (345 ns) (Overruns: 2838) update_wall_time+0x384/0x8c0 -> clocksource_get_next (1141 ns) (Overruns: 2838) do_timer+0x23/0x100 -> update_wall_time (3882 ns) (Overruns: 2838) tick_do_update_jiffies64+0xbf/0x160 -> do_timer (5339 ns) (Overruns: 2838) tick_sched_timer+0x6a/0xf0 -> tick_do_update_jiffies64 (7209 ns) (Overruns: 2838) vgacon_set_cursor_size+0x98/0x120 -> native_io_delay (2613 ns) (Overruns: 274) vgacon_cursor+0x16e/0x1d0 -> vgacon_set_cursor_size (33151 ns) (Overruns: 274) set_cursor+0x5f/0x80 -> vgacon_cursor (36432 ns) (Overruns: 274) con_flush_chars+0x34/0x40 -> set_cursor (38790 ns) (Overruns: 274) release_console_sem+0x1ec/0x230 -> up (721 ns) (Overruns: 274) release_console_sem+0x225/0x230 -> wake_up_klogd (316 ns) (Overruns: 274) con_flush_chars+0x39/0x40 -> release_console_sem (2996 ns) (Overruns: 274) con_write+0x22/0x30 -> con_flush_chars (46067 ns) (Overruns: 274) n_tty_write+0x1cc/0x360 -> con_write (292670 ns) (Overruns: 274) smp_apic_timer_interrupt+0x2a/0x90 -> native_apic_mem_write (330 ns) (Overruns: 274) irq_enter+0x17/0x70 -> idle_cpu (413 ns) (Overruns: 274) smp_apic_timer_interrupt+0x2f/0x90 -> irq_enter (1525 ns) (Overruns: 274) ktime_get_ts+0x40/0x70 -> getnstimeofday (465 ns) (Overruns: 274) ktime_get_ts+0x60/0x70 -> set_normalized_timespec (436 ns) (Overruns: 274) ktime_get+0x16/0x30 -> ktime_get_ts (2501 ns) (Overruns: 274) hrtimer_interrupt+0x77/0x1a0 -> ktime_get (3439 ns) (Overruns: 274) Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include')
-rw-r--r--include/linux/ftrace.h2
-rw-r--r--include/linux/sched.h1
2 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index f1af1aab00e..f7ba4ea5e12 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -318,6 +318,8 @@ struct ftrace_retfunc {
unsigned long func; /* Current function */
unsigned long long calltime;
unsigned long long rettime;
+ /* Number of functions that overran the depth limit for current task */
+ unsigned long overrun;
};
#ifdef CONFIG_FUNCTION_RET_TRACER
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 61c8cc36028..c8e0db46420 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2016,6 +2016,7 @@ static inline void setup_thread_stack(struct task_struct *p, struct task_struct
* used.
*/
task_thread_info(p)->curr_ret_stack = -1;
+ atomic_set(&task_thread_info(p)->trace_overrun, 0);
#endif
}