From: Steven Rostedt When sleep_time is off the function profiler ignores the time that a task is scheduled out. When the task is scheduled out a timestamp is taken. When the task is scheduled back in, the timestamp is compared to the current time and the saved calltimes are adjusted accordingly. But when stopping the function profiler, the sched switch hook that does this adjustment was stopped before shutting down the tracer. This allowed some tasks to not get their timestamps set when they scheduled out. When the function profiler started again, this would skew the times of the scheduler functions. This patch moves the stopping of the sched switch to after the function profiler is stopped. It also ignores zero set calltimes, which may happen on start up. Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 3bcb340..8c9c293 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -666,6 +666,10 @@ static void profile_graph_return(struct ftrace_graph_ret *trace) if (!stat->hash || !ftrace_profile_enabled) goto out; + /* If the calltime was zero'd ignore it */ + if (!trace->calltime) + goto out; + calltime = trace->rettime - trace->calltime; if (!(trace_flags & TRACE_ITER_GRAPH_TIME)) { @@ -3357,11 +3361,11 @@ void unregister_ftrace_graph(void) goto out; ftrace_graph_active--; - unregister_trace_sched_switch(ftrace_graph_probe_sched_switch); ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub; ftrace_graph_entry = ftrace_graph_entry_stub; ftrace_shutdown(FTRACE_STOP_FUNC_RET); unregister_pm_notifier(&ftrace_suspend_notifier); + unregister_trace_sched_switch(ftrace_graph_probe_sched_switch); out: mutex_unlock(&ftrace_lock); -- 1.7.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/