aboutsummaryrefslogtreecommitdiffstats
path: root/kernel
diff options
context:
space:
mode:
authorSteven Rostedt <srostedt@redhat.com>2009-01-15 23:40:11 -0500
committerIngo Molnar <mingo@elte.hu>2009-01-21 09:21:30 -0500
commit1092307d582a7566d23779c304cf86f3075ac5f0 (patch)
tree89b70760ec229b593d4ea9c35084ef44a68b2ec4 /kernel
parenta442e5e0a2011af5b2d1f118fee0a8f9079f1d88 (diff)
trace: set max latency variable to zero on default
Impact: trace max latencies on start of latency tracing This patch sets the max latency to zero whenever one of the irq variant tracers or the wakeup tracer is set to current tracer. Most developers expect to see output when starting up a latency tracer. But since the max_latency is already set to max, and it takes a latency greater than max_latency to be recorded, there is no trace. This is not the expected behavior and has even confused myself. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace.c2
-rw-r--r--kernel/trace/trace_irqsoff.c1
-rw-r--r--kernel/trace/trace_sched_wakeup.c1
3 files changed, 3 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4d89e84f0f4b..17bb88d86ac2 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -40,7 +40,7 @@
40 40
41#define TRACE_BUFFER_FLAGS (RB_FL_OVERWRITE) 41#define TRACE_BUFFER_FLAGS (RB_FL_OVERWRITE)
42 42
43unsigned long __read_mostly tracing_max_latency = (cycle_t)ULONG_MAX; 43unsigned long __read_mostly tracing_max_latency;
44unsigned long __read_mostly tracing_thresh; 44unsigned long __read_mostly tracing_thresh;
45 45
46/* 46/*
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 7c2e326bbc8b..62a78d943534 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -380,6 +380,7 @@ static void stop_irqsoff_tracer(struct trace_array *tr)
380 380
381static void __irqsoff_tracer_init(struct trace_array *tr) 381static void __irqsoff_tracer_init(struct trace_array *tr)
382{ 382{
383 tracing_max_latency = 0;
383 irqsoff_trace = tr; 384 irqsoff_trace = tr;
384 /* make sure that the tracer is visible */ 385 /* make sure that the tracer is visible */
385 smp_wmb(); 386 smp_wmb();
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 43586b689e31..42ae1e77b6b3 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -333,6 +333,7 @@ static void stop_wakeup_tracer(struct trace_array *tr)
333 333
334static int wakeup_tracer_init(struct trace_array *tr) 334static int wakeup_tracer_init(struct trace_array *tr)
335{ 335{
336 tracing_max_latency = 0;
336 wakeup_trace = tr; 337 wakeup_trace = tr;
337 start_wakeup_tracer(tr); 338 start_wakeup_tracer(tr);
338 return 0; 339 return 0;