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authorSteven Rostedt <srostedt@redhat.com>2010-04-27 21:04:24 -0400
committerSteven Rostedt <rostedt@goodmis.org>2010-04-27 21:04:24 -0400
commit37e44bc50d91df1fe7edcf6f02fe168c6d802e64 (patch)
tree40058a2b27e94400dc4345ba13b334fb732ae532 /kernel/trace
parente330b3bcd83199dd63a819d8d12e40f9edae6c77 (diff)
downloadlwn-37e44bc50d91df1fe7edcf6f02fe168c6d802e64.tar.gz
lwn-37e44bc50d91df1fe7edcf6f02fe168c6d802e64.zip
tracing: Fix sleep time function profiling
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 <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/ftrace.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3bcb340d6f02..8c9c2934c45f 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);