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Date: Tue, 13 Sep 2011 16:03:34 +0200
From: Jiri Olsa <jolsa@...hat.com>
To: rostedt@...dmis.org, fweisbec@...il.com, mingo@...hat.com
Cc: linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...hat.com>
Subject: [PATCH] tracing/latency: Fix header output for latency tracers
In case the the graph tracer (CONFIG_FUNCTION_GRAPH_TRACER) or even the
function tracer (CONFIG_FUNCTION_TRACER) are not set, the latency tracers
do not display proper latency header.
The involved/fixed latency tracers are:
wakeup_rt
wakeup
preemptirqsoff
preemptoff
irqsoff
The patch adds proper handling of tracer configuration options for latency
tracers, and displaying correct header info accordingly.
* The current output (for wakeup tracer) with both graph and function
tracers disabled is:
# tracer: wakeup
#
cat-1163 0d..4 1us : 1163:120:R + [000] 6: 0:R migration/0
cat-1163 0d..4 2us+: ttwu_do_activate.clone.1 <-try_to_wake_up
cat-1163 0d..3 4us : __schedule <-preempt_schedule
cat-1163 0d..3 4us : 1163:120:R ==> [000] 6: 0:R migration/0
* The fixed output is:
# tracer: wakeup
#
# wakeup latency trace v1.1.5 on 3.1.0-rc4-tip+
# --------------------------------------------------------------------
# latency: 91 us, #4/4, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
# -----------------
# | task: watchdog/0-7 (uid:0 nice:0 policy:1 rt_prio:99)
# -----------------
#
<idle>-0 0d.h5 1us : 0:120:R + [000] 7: 0:R watchdog/0
<idle>-0 0d.h5 2us+: ttwu_do_activate.clone.1 <-try_to_wake_up
<idle>-0 0d..3 17us : __schedule <-schedule
<idle>-0 0d..3 17us : 0:120:R ==> [000] 7: 0:R watchdog/0
* There's slightly different output (for wakeup_rt tracer) when function
tracer is enabled, currently:
# tracer: wakeup_rt
#
cat-1168 1d..4 0us : 1168:120:R + [001] 8: 0:R migration/1
cat-1168 1d..4 1us : ttwu_do_activate.clone.1 <-try_to_wake_up
cat-1168 1d..3 1us : check_preempt_curr <-ttwu_do_wakeup
...
* After the fix:
# tracer: wakeup_rt
#
# wakeup_rt latency trace v1.1.5 on 3.1.0-rc4-tip+
# --------------------------------------------------------------------
# latency: 209 us, #113/113, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
# -----------------
# | task: watchdog/0-7 (uid:0 nice:0 policy:1 rt_prio:99)
# -----------------
#
# _------=> CPU#
# / _-----=> irqs-off
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| / delay
# cmd pid ||||| time | caller
# \ / ||||| \ | /
cat-1168 1d..4 0us : 1168:120:R + [001] 8: 0:R migration/1
cat-1168 1d..4 1us : ttwu_do_activate.clone.1 <-try_to_wake_up
cat-1168 1d..3 1us : check_preempt_curr <-ttwu_do_wakeup
...
Signed-off-by: Jiri Olsa <jolsa@...hat.com>
---
kernel/trace/trace.c | 12 ++++++++++++
kernel/trace/trace.h | 1 +
kernel/trace/trace_irqsoff.c | 13 ++++++++++++-
kernel/trace/trace_sched_wakeup.c | 13 ++++++++++++-
4 files changed, 37 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e5df02c..7086345 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2139,6 +2139,18 @@ enum print_line_t print_trace_line(struct trace_iterator *iter)
return print_trace_fmt(iter);
}
+void trace_latency_header(struct seq_file *m)
+{
+ struct trace_iterator *iter = m->private;
+
+ /* print nothing if the buffers are empty */
+ if (trace_empty(iter))
+ return;
+
+ if (iter->iter_flags & TRACE_FILE_LAT_FMT)
+ print_trace_header(m, iter);
+}
+
void trace_default_header(struct seq_file *m)
{
struct trace_iterator *iter = m->private;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 616846b..db40865 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -370,6 +370,7 @@ void trace_graph_function(struct trace_array *tr,
unsigned long ip,
unsigned long parent_ip,
unsigned long flags, int pc);
+void trace_latency_header(struct seq_file *m);
void trace_default_header(struct seq_file *m);
void print_trace_header(struct seq_file *m, struct trace_iterator *iter);
int trace_empty(struct trace_iterator *iter);
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 667aa8c..2a0aee6 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -280,9 +280,20 @@ static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
}
static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
-static void irqsoff_print_header(struct seq_file *s) { }
static void irqsoff_trace_open(struct trace_iterator *iter) { }
static void irqsoff_trace_close(struct trace_iterator *iter) { }
+
+#ifdef CONFIG_FUNCTION_TRACER
+static void irqsoff_print_header(struct seq_file *s)
+{
+ trace_default_header(s);
+}
+#else
+static void irqsoff_print_header(struct seq_file *s)
+{
+ trace_latency_header(s);
+}
+#endif /* CONFIG_FUNCTION_TRACER */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
/*
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index e4a70c0..ff791ea 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -280,9 +280,20 @@ static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
}
static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
-static void wakeup_print_header(struct seq_file *s) { }
static void wakeup_trace_open(struct trace_iterator *iter) { }
static void wakeup_trace_close(struct trace_iterator *iter) { }
+
+#ifdef CONFIG_FUNCTION_TRACER
+static void wakeup_print_header(struct seq_file *s)
+{
+ trace_default_header(s);
+}
+#else
+static void wakeup_print_header(struct seq_file *s)
+{
+ trace_latency_header(s);
+}
+#endif /* CONFIG_FUNCTION_TRACER */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
/*
--
1.7.1
--
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