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Subject[PATCHv2] tracing/latency: Fix header output for latency tracers
On Fri, Nov 04, 2011 at 10:24:46PM -0400, Steven Rostedt wrote:
> Sorry for the late reply, I'm still purging through my Inbox from over
> the week in Prague.
>
>
> On Tue, 2011-09-13 at 16:03 +0200, Jiri Olsa wrote:
> > 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
>
> Why the above header? Why not just use the latency header for all of
> them?

ops, you're right I forgot to call the print_lat_help_header function,
attaching PATCHv2

thanks,
jirka


---
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
#
<idle>-0 0d.h5 1us+: 0:120:R + [000] 7: 0:R watchdog/0
<idle>-0 0d.h5 3us+: ttwu_do_activate.clone.1 <-try_to_wake_up
...

* The fixed output is:

# tracer: wakeup
#
# wakeup latency trace v1.1.5 on 3.1.0-tip+
# --------------------------------------------------------------------
# latency: 55 us, #4/4, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
# -----------------
# | task: migration/0-6 (uid:0 nice:0 policy:1 rt_prio:99)
# -----------------
#
# _------=> CPU#
# / _-----=> irqs-off
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| / delay
# cmd pid ||||| time | caller
# \ / ||||| \ | /
cat-1129 0d..4 1us : 1129:120:R + [000] 6: 0:R migration/0
cat-1129 0d..4 2us+: ttwu_do_activate.clone.1 <-try_to_wake_up
* The current output (for wakeup tracer) with only function
tracer enabled is:

# tracer: wakeup
#
cat-1140 0d..4 1us+: 1140:120:R + [000] 6: 0:R migration/0
cat-1140 0d..4 2us : ttwu_do_activate.clone.1 <-try_to_wake_up

* The fixed output is:
# tracer: wakeup
#
# wakeup latency trace v1.1.5 on 3.1.0-tip+
# --------------------------------------------------------------------
# latency: 207 us, #109/109, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
# -----------------
# | task: watchdog/1-12 (uid:0 nice:0 policy:1 rt_prio:99)
# -----------------
#
# _------=> CPU#
# / _-----=> irqs-off
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| / delay
# cmd pid ||||| time | caller
# \ / ||||| \ | /
<idle>-0 1d.h5 1us+: 0:120:R + [001] 12: 0:R watchdog/1
<idle>-0 1d.h5 3us : ttwu_do_activate.clone.1 <-try_to_wake_up
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
kernel/trace/trace.c | 15 +++++++++++++++
kernel/trace/trace.h | 1 +
kernel/trace/trace_irqsoff.c | 13 ++++++++++++-
kernel/trace/trace_sched_wakeup.c | 13 ++++++++++++-
4 files changed, 40 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f2bd275..9e158cc 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2140,6 +2140,21 @@ 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);
+
+ if (!(trace_flags & TRACE_ITER_VERBOSE))
+ print_lat_help_header(m);
+}
+
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 092e1f8..f8ec229 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 20dad0d..99d20e9 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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