2009-03-31 04:02:55

by Zhao Lei

Subject: [PATCH 1/2] Add check of sched_stopped for probe_sched_wakeup

We need check sched_stopped in probe_sched_wakeup() to stop tracing when an
user stops it.

But current code can also do the right thing(stop tracing after
echo 0 > tracing_enabled) just because tracing_sched_wakeup_trace() can return
on buffer->record_disabled.

Signed-off-by: Zhao Lei <[email protected]>
---
kernel/trace/trace_sched_switch.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index de35f20..9117cea 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -62,6 +62,9 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee, int success)
pc = preempt_count();
tracing_record_cmdline(current);

+ if (sched_stopped)
+ return;
+
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = ctx_trace->data[cpu];
--
1.5.5.3

2009-03-31 04:03:52

by Zhao Lei

Subject: [PATCH 2/2] ftrace: Clean up enable logic for sched_switch

Unify sched_switch and sched_wakeup's action to following logic:
Do record_cmdline when start_cmdline_record() called.
Trace event when trace is inited and started.

Signed-off-by: Zhao Lei <[email protected]>
---
kernel/trace/trace_sched_switch.c | 10 +++++-----
1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 9117cea..b6a0938 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -29,13 +29,13 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
int cpu;
int pc;

- if (!sched_ref || sched_stopped)
+ if (!likely(sched_ref))
return;

tracing_record_cmdline(prev);
tracing_record_cmdline(next);

- if (!tracer_enabled)
+ if (!tracer_enabled || sched_stopped)
return;

pc = preempt_count();
@@ -56,15 +56,15 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee, int success)
unsigned long flags;
int cpu, pc;

- if (!likely(tracer_enabled))
+ if (!likely(sched_ref))
return;

- pc = preempt_count();
tracing_record_cmdline(current);

- if (sched_stopped)
+ if (!tracer_enabled || sched_stopped)
return;

+ pc = preempt_count();
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = ctx_trace->data[cpu];
--
1.5.5.3

2009-03-31 04:12:30

by Steven Rostedt

Subject: Re: [PATCH 2/2] ftrace: Clean up enable logic for sched_switch

On Tue, 31 Mar 2009, Zhaolei wrote:
>
> diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
> index 9117cea..b6a0938 100644
> --- a/kernel/trace/trace_sched_switch.c
> +++ b/kernel/trace/trace_sched_switch.c
> @@ -29,13 +29,13 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
> int cpu;
> int pc;
>
> - if (!sched_ref || sched_stopped)
> + if (!likely(sched_ref))

That should be:

if (unlikely(!sched_ref))

> return;
>
> tracing_record_cmdline(prev);
> tracing_record_cmdline(next);
>
> - if (!tracer_enabled)
> + if (!tracer_enabled || sched_stopped)
> return;
>
> pc = preempt_count();
> @@ -56,15 +56,15 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee, int success)
> unsigned long flags;
> int cpu, pc;
>
> - if (!likely(tracer_enabled))
> + if (!likely(sched_ref))

Same here.

-- Steve

> return;
>
> - pc = preempt_count();
> tracing_record_cmdline(current);
>
> - if (sched_stopped)
> + if (!tracer_enabled || sched_stopped)
> return;
>
> + pc = preempt_count();
> local_irq_save(flags);
> cpu = raw_smp_processor_id();
> data = ctx_trace->data[cpu];
> --
> 1.5.5.3
>
>
>