On Mon, 2 Nov 2015 17:42:43 -0500 Mathieu Desnoyers <[email protected]> wrote:
> In order to use ftrace tracers to generate tracepoints without doing > tracing to its own hardcoded ring buffers, add a ftrace-buffer option > (default: 1). When set to 0, it disables tracing into the ftrace > hardcoded buffers. > This needs a more in depth change log. I have no idea why this is needed. Also, the trace_options code have been redesigned, and this won't apply to it (see linux-next). Also, if this is only for irqsoff latency tracers, it should be a tracer option, not a global one. -- Steve > Signed-off-by: Mathieu Desnoyers <[email protected]> > CC: Thomas Gleixner <[email protected]> > CC: Steven Rostedt <[email protected]> > CC: Ingo Molnar <[email protected]> > CC: Peter Zijlstra <[email protected]> > --- > kernel/trace/trace.c | 4 +++- > kernel/trace/trace.h | 1 + > kernel/trace/trace_irqsoff.c | 19 +++++++++++-------- > 3 files changed, 15 insertions(+), 9 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 6e79408..d664f0e 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -472,7 +472,8 @@ static inline void trace_access_lock_init(void) > unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK | > TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME | > TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE | > - TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS | TRACE_ITER_FUNCTION; > + TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS | TRACE_ITER_FUNCTION | > + TRACE_ITER_FTRACE_BUFFER; > > static void tracer_tracing_on(struct trace_array *tr) > { > @@ -862,6 +863,7 @@ static const char *trace_options[] = { > "irq-info", > "markers", > "function-trace", > + "ftrace-buffer", > NULL > }; > > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 74bde81..29968e1 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -930,6 +930,7 @@ enum trace_iterator_flags { > TRACE_ITER_IRQ_INFO = 0x800000, > TRACE_ITER_MARKERS = 0x1000000, > TRACE_ITER_FUNCTION = 0x2000000, > + TRACE_ITER_FTRACE_BUFFER = 0x4000000, > }; > > /* > diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c > index 8523ea3..3e5635d 100644 > --- a/kernel/trace/trace_irqsoff.c > +++ b/kernel/trace/trace_irqsoff.c > @@ -334,9 +334,11 @@ check_critical_timing(struct trace_array *tr, > if (!report_latency(tr, delta)) > goto out_unlock; > > - __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc); > - /* Skip 5 functions to get to the irq/preempt enable function */ > - __trace_stack(tr, flags, 5, pc); > + if (trace_flags & TRACE_ITER_FTRACE_BUFFER) { > + __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc); > + /* Skip 5 functions to get to the irq/preempt enable function */ > + __trace_stack(tr, flags, 5, pc); > + } > > if (data->critical_sequence != max_sequence) > goto out_unlock; > @@ -356,7 +358,8 @@ out_unlock: > out: > data->critical_sequence = max_sequence; > data->preempt_timestamp = ftrace_now(cpu); > - __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc); > + if (trace_flags & TRACE_ITER_FTRACE_BUFFER) > + __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc); > } > > static inline void > @@ -387,9 +390,8 @@ start_critical_timing(unsigned long ip, unsigned long > parent_ip) > data->critical_start = parent_ip ? : ip; > > local_save_flags(flags); > - > - __trace_function(tr, ip, parent_ip, flags, preempt_count()); > - > + if (trace_flags & TRACE_ITER_FTRACE_BUFFER) > + __trace_function(tr, ip, parent_ip, flags, preempt_count()); > per_cpu(tracing_cpu, cpu) = 1; > > atomic_dec(&data->disabled); > @@ -422,7 +424,8 @@ stop_critical_timing(unsigned long ip, unsigned long > parent_ip) > atomic_inc(&data->disabled); > > local_save_flags(flags); > - __trace_function(tr, ip, parent_ip, flags, preempt_count()); > + if (trace_flags & TRACE_ITER_FTRACE_BUFFER) > + __trace_function(tr, ip, parent_ip, flags, preempt_count()); > check_critical_timing(tr, data, parent_ip ? : ip, cpu); > data->critical_start = 0; > atomic_dec(&data->disabled); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
