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authorSteven Rostedt <srostedt@redhat.com>2009-09-01 11:06:29 -0400
committerSteven Rostedt <rostedt@goodmis.org>2009-09-04 18:44:22 -0400
commit2f26ebd549b9ab55ac756b836ec759c11fe93f81 (patch)
tree0f6fb154e2b5e9233a683b3267e5efe862a846f4 /kernel/trace/trace_sched_wakeup.c
parent76f0d07376388f32698ba51b6090a26b90c1342f (diff)
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tracing: use timestamp to determine start of latency traces
Currently the latency tracers reset the ring buffer. Unfortunately if a commit is in process (due to a trace event), this can corrupt the ring buffer. When this happens, the ring buffer will detect the corruption and then permanently disable the ring buffer. The bug does not crash the system, but it does prevent further tracing after the bug is hit. Instead of reseting the trace buffers, the timestamp of the start of the trace is used instead. The buffers will still contain the previous data, but the output will not count any data that is before the timestamp of the trace. Note, this only affects the static trace output (trace) and not the runtime trace output (trace_pipe). The runtime trace output does not make sense for the latency tracers anyway. Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace_sched_wakeup.c')
-rw-r--r--kernel/trace/trace_sched_wakeup.c7
1 files changed, 2 insertions, 5 deletions
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index eacb2722517..ad69f105a7c 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -186,11 +186,6 @@ out:
static void __wakeup_reset(struct trace_array *tr)
{
- int cpu;
-
- for_each_possible_cpu(cpu)
- tracing_reset(tr, cpu);
-
wakeup_cpu = -1;
wakeup_prio = -1;
@@ -204,6 +199,8 @@ static void wakeup_reset(struct trace_array *tr)
{
unsigned long flags;
+ tracing_reset_online_cpus(tr);
+
local_irq_save(flags);
__raw_spin_lock(&wakeup_lock);
__wakeup_reset(tr);