Re: [PATCH] trace: add graph output support for wakeup tracer

Steven Rostedt
2010-09-06T20:14:33Z

On Mon, 2010-08-23 at 12:22 +0200, Jiri Olsa wrote:
> hi,
> any feedback?
>
> thanks,
> jirka
>
> On Thu, Aug 05, 2010 at 04:57:27PM +0200, Jiri Olsa wrote:
> > hi,
> >
> > adding function graph output to irqsoff tracer.
> > The graph output is enabled by setting new 'display-graph' trace option.

Ah, the irqsoff tracer update is in mainline. I guess I missed the
wakeup one.

62b915f1060996a8e1f69be50e3b8e9e43b710cb

Today is a US holiday, I'll investigate this tomorrow.

-- Steve

> >
> > wbr,
> > jirka
> >
> >
> > Signed-off-by: Jiri Olsa <jolsa@redhat.com>
> > ---
> > kernel/trace/trace_sched_wakeup.c | 274 +++++++++++++++++++++++++++++++++++--
> > 1 files changed, 264 insertions(+), 10 deletions(-)
> >
> > diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
> > index 4086eae..b576141 100644
> > --- a/kernel/trace/trace_sched_wakeup.c
> > +++ b/kernel/trace/trace_sched_wakeup.c
> > @@ -31,13 +31,33 @@ static int wakeup_rt;
> > static arch_spinlock_t wakeup_lock =
> > (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
> >
> > +static void wakeup_reset(struct trace_array *tr);
> > static void __wakeup_reset(struct trace_array *tr);
> > +static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
> > +static void wakeup_graph_return(struct ftrace_graph_ret *trace);
> >
> > static int save_lat_flag;
> >
> > +#define TRACE_DISPLAY_GRAPH 1
> > +
> > +static struct tracer_opt trace_opts[] = {
> > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> > + /* display latency trace as call graph */
> > + { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
> > +#endif
> > + { } /* Empty entry */
> > +};
> > +
> > +static struct tracer_flags tracer_flags = {
> > + .val = 0,
> > + .opts = trace_opts,
> > +};
> > +
> > +#define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
> > +
> > #ifdef CONFIG_FUNCTION_TRACER
> > /*
> > - * irqsoff uses its own tracer function to keep the overhead down:
> > + * wakeup uses its own tracer function to keep the overhead down:
> > */
> > static void
> > wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
> > @@ -80,8 +100,234 @@ static struct ftrace_ops trace_ops __read_mostly =
> > {
> > .func = wakeup_tracer_call,
> > };
> > +
> > +static int start_func_tracer(int graph)
> > +{
> > + int ret;
> > +
> > + if (!graph)
> > + ret = register_ftrace_function(&trace_ops);
> > + else
> > + ret = register_ftrace_graph(&wakeup_graph_return,
> > + &wakeup_graph_entry);
> > +
> > + if (!ret && tracing_is_enabled())
> > + tracer_enabled = 1;
> > + else
> > + tracer_enabled = 0;
> > +
> > + return ret;
> > +}
> > +
> > +static void stop_func_tracer(int graph)
> > +{
> > + tracer_enabled = 0;
> > +
> > + if (!graph)
> > + unregister_ftrace_function(&trace_ops);
> > + else
> > + unregister_ftrace_graph();
> > +}
> > +
> > #endif /* CONFIG_FUNCTION_TRACER */
> >
> > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> > +static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
> > +{
> > +
> > + if (!(bit & TRACE_DISPLAY_GRAPH))
> > + return -EINVAL;
> > +
> > + if (!(is_graph() ^ set))
> > + return 0;
> > +
> > + stop_func_tracer(!set);
> > + wakeup_reset(wakeup_trace);
> > +
> > + return start_func_tracer(set);
> > +}
> > +
> > +static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
> > +{
> > + struct trace_array *tr = wakeup_trace;
> > + struct trace_array_cpu *data;
> > + unsigned long flags;
> > + long disabled;
> > + int cpu, pc, ret = 0;
> > +
> > + if (likely(!wakeup_task))
> > + return 0;
> > +
> > + pc = preempt_count();
> > + preempt_disable_notrace();
> > +
> > + cpu = raw_smp_processor_id();
> > + if (cpu != wakeup_current_cpu)
> > + goto out_enable;
> > +
> > + data = tr->data[cpu];
> > + disabled = atomic_inc_return(&data->disabled);
> > + if (unlikely(disabled != 1))
> > + goto out;
> > +
> > + local_irq_save(flags);
> > + ret = __trace_graph_entry(tr, trace, flags, pc);
> > + local_irq_restore(flags);
> > +
> > + out:
> > + atomic_dec(&data->disabled);
> > +
> > + out_enable:
> > + preempt_enable_notrace();
> > + return ret;
> > +}
> > +
> > +static void wakeup_graph_return(struct ftrace_graph_ret *trace)
> > +{
> > + struct trace_array *tr = wakeup_trace;
> > + struct trace_array_cpu *data;
> > + unsigned long flags;
> > + long disabled;
> > + int cpu, pc;
> > +
> > + if (likely(!wakeup_task))
> > + return;
> > +
> > + pc = preempt_count();
> > + preempt_disable_notrace();
> > +
> > + cpu = raw_smp_processor_id();
> > + if (cpu != wakeup_current_cpu)
> > + goto out_enable;
> > +
> > + data = tr->data[cpu];
> > + disabled = atomic_inc_return(&data->disabled);
> > + if (unlikely(disabled != 1))
> > + goto out;
> > +
> > + local_irq_save(flags);
> > + __trace_graph_return(tr, trace, flags, pc);
> > + local_irq_restore(flags);
> > +
> > + out:
> > + atomic_dec(&data->disabled);
> > +
> > + out_enable:
> > + preempt_enable_notrace();
> > + return;
> > +}
> > +
> > +static void wakeup_trace_open(struct trace_iterator *iter)
> > +{
> > + if (is_graph())
> > + graph_trace_open(iter);
> > +}
> > +
> > +static void wakeup_trace_close(struct trace_iterator *iter)
> > +{
> > + if (iter->private)
> > + graph_trace_close(iter);
> > +}
> > +
> > +#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC)
> > +
> > +static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
> > +{
> > + u32 flags = GRAPH_TRACER_FLAGS;
> > +
> > + if (trace_flags & TRACE_ITER_LATENCY_FMT)
> > + flags |= TRACE_GRAPH_PRINT_DURATION;
> > + else
> > + flags |= TRACE_GRAPH_PRINT_ABS_TIME;
> > +
> > + /*
> > + * In graph mode call the graph tracer output function,
> > + * otherwise go with the TRACE_FN event handler
> > + */
> > + if (is_graph())
> > + return print_graph_function_flags(iter, flags);
> > +
> > + return TRACE_TYPE_UNHANDLED;
> > +}
> > +
> > +static void wakeup_print_header(struct seq_file *s)
> > +{
> > + if (is_graph()) {
> > + struct trace_iterator *iter = s->private;
> > + u32 flags = GRAPH_TRACER_FLAGS;
> > +
> > + if (trace_flags & TRACE_ITER_LATENCY_FMT) {
> > + /* print nothing if the buffers are empty */
> > + if (trace_empty(iter))
> > + return;
> > +
> > + print_trace_header(s, iter);
> > + flags |= TRACE_GRAPH_PRINT_DURATION;
> > + } else
> > + flags |= TRACE_GRAPH_PRINT_ABS_TIME;
> > +
> > + print_graph_headers_flags(s, flags);
> > + } else
> > + trace_default_header(s);
> > +}
> > +
> > +static void
> > +trace_graph_function(struct trace_array *tr,
> > + unsigned long ip, unsigned long flags, int pc)
> > +{
> > + u64 time = trace_clock_local();
> > + struct ftrace_graph_ent ent = {
> > + .func = ip,
> > + .depth = 0,
> > + };
> > + struct ftrace_graph_ret ret = {
> > + .func = ip,
> > + .depth = 0,
> > + .calltime = time,
> > + .rettime = time,
> > + };
> > +
> > + __trace_graph_entry(tr, &ent, flags, pc);
> > + __trace_graph_return(tr, &ret, flags, pc);
> > +}
> > +
> > +static void
> > +__trace_function(struct trace_array *tr,
> > + unsigned long ip, unsigned long parent_ip,
> > + unsigned long flags, int pc)
> > +{
> > + if (!is_graph())
> > + trace_function(tr, ip, parent_ip, flags, pc);
> > + else {
> > + trace_graph_function(tr, parent_ip, flags, pc);
> > + trace_graph_function(tr, ip, flags, pc);
> > + }
> > +}
> > +
> > +#else
> > +#define __trace_function trace_function
> > +
> > +static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
> > +{
> > + return -EINVAL;
> > +}
> > +
> > +static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
> > +{
> > + return -1;
> > +}
> > +
> > +static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
> > +{
> > + return TRACE_TYPE_UNHANDLED;
> > +}
> > +
> > +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) { }
> > +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> > +
> > /*
> > * Should this new latency be reported/recorded?
> > */
> > @@ -152,7 +398,7 @@ probe_wakeup_sched_switch(void *ignore,
> > /* The task we are waiting for is waking up */
> > data = wakeup_trace->data[wakeup_cpu];
> >
> > - trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
> > + __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
> > tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
> >
> > T0 = data->preempt_timestamp;
> > @@ -252,7 +498,7 @@ probe_wakeup(void *ignore, struct task_struct *p, int success)
> > * is not called by an assembly function (where as schedule is)
> > * it should be safe to use it here.
> > */
> > - trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
> > + __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
> >
> > out_locked:
> > arch_spin_unlock(&wakeup_lock);
> > @@ -303,12 +549,8 @@ static void start_wakeup_tracer(struct trace_array *tr)
> > */
> > smp_wmb();
> >
> > - register_ftrace_function(&trace_ops);
> > -
> > - if (tracing_is_enabled())
> > - tracer_enabled = 1;
> > - else
> > - tracer_enabled = 0;
> > + if (start_func_tracer(is_graph()))
> > + printk(KERN_ERR "failed to start wakeup tracer\n");
> >
> > return;
> > fail_deprobe_wake_new:
> > @@ -320,7 +562,7 @@ fail_deprobe:
> > static void stop_wakeup_tracer(struct trace_array *tr)
> > {
> > tracer_enabled = 0;
> > - unregister_ftrace_function(&trace_ops);
> > + stop_func_tracer(is_graph());
> > unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
> > unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
> > unregister_trace_sched_wakeup(probe_wakeup, NULL);
> > @@ -379,9 +621,15 @@ static struct tracer wakeup_tracer __read_mostly =
> > .start = wakeup_tracer_start,
> > .stop = wakeup_tracer_stop,
> > .print_max = 1,
> > + .print_header = wakeup_print_header,
> > + .print_line = wakeup_print_line,
> > + .flags = &tracer_flags,
> > + .set_flag = wakeup_set_flag,
> > #ifdef CONFIG_FTRACE_SELFTEST
> > .selftest = trace_selftest_startup_wakeup,
> > #endif
> > + .open = wakeup_trace_open,
> > + .close = wakeup_trace_close,
> > .use_max_tr = 1,
> > };
> >
> > @@ -394,9 +642,15 @@ static struct tracer wakeup_rt_tracer __read_mostly =
> > .stop = wakeup_tracer_stop,
> > .wait_pipe = poll_wait_pipe,
> > .print_max = 1,
> > + .print_header = wakeup_print_header,
> > + .print_line = wakeup_print_line,
> > + .flags = &tracer_flags,
> > + .set_flag = wakeup_set_flag,
> > #ifdef CONFIG_FTRACE_SELFTEST
> > .selftest = trace_selftest_startup_wakeup,
> > #endif
> > + .open = wakeup_trace_open,
> > + .close = wakeup_trace_close,
> > .use_max_tr = 1,
> > };
> >
> > --
> > 1.7.2
> >
> > --
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