Hi Namhyung, On Fri, 2017-07-14 at 14:25 +0900, Namhyung Kim wrote: > On Mon, Jun 26, 2017 at 05:49:04PM -0500, Tom Zanussi wrote: > > Define a new function, tracing_set_time_stamp_abs(), which can be used > > to enable or disable the use of absolute timestamps rather than time > > deltas for a trace array. > > > > This resets the buffer to prevent a mix of time deltas and absolute > > timestamps. > > > > Only the interface is added here; a subsequent patch will add the > > underlying implementation. > > > > Signed-off-by: Tom Zanussi <[email protected]> > > --- > > include/linux/ring_buffer.h | 2 ++ > > kernel/trace/ring_buffer.c | 11 +++++++++++ > > kernel/trace/trace.c | 25 ++++++++++++++++++++++++- > > kernel/trace/trace.h | 2 ++ > > 4 files changed, 39 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h > > index ee9b461..28e3472 100644 > > --- a/include/linux/ring_buffer.h > > +++ b/include/linux/ring_buffer.h > > @@ -180,6 +180,8 @@ void ring_buffer_normalize_time_stamp(struct > > ring_buffer *buffer, > > int cpu, u64 *ts); > > void ring_buffer_set_clock(struct ring_buffer *buffer, > > u64 (*clock)(void)); > > +void ring_buffer_set_time_stamp_abs(struct ring_buffer *buffer, bool abs); > > +bool ring_buffer_time_stamp_abs(struct ring_buffer *buffer); > > > > size_t ring_buffer_page_len(void *page); > > > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > > index 4ae268e..f544738 100644 > > --- a/kernel/trace/ring_buffer.c > > +++ b/kernel/trace/ring_buffer.c > > @@ -485,6 +485,7 @@ struct ring_buffer { > > u64 (*clock)(void); > > > > struct rb_irq_work irq_work; > > + bool time_stamp_abs; > > }; > > > > struct ring_buffer_iter { > > @@ -1379,6 +1380,16 @@ void ring_buffer_set_clock(struct ring_buffer > > *buffer, > > buffer->clock = clock; > > } > > > > +void ring_buffer_set_time_stamp_abs(struct ring_buffer *buffer, bool abs) > > +{ > > + buffer->time_stamp_abs = abs; > > +} > > + > > +bool ring_buffer_time_stamp_abs(struct ring_buffer *buffer) > > +{ > > + return buffer->time_stamp_abs; > > +} > > + > > static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); > > > > static inline unsigned long rb_page_entries(struct buffer_page *bpage) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > > index 19ac208..da8cd51 100644 > > --- a/kernel/trace/trace.c > > +++ b/kernel/trace/trace.c > > @@ -2169,7 +2169,7 @@ struct ring_buffer_event * > > > > *current_rb = trace_file->tr->trace_buffer.buffer; > > > > - if ((trace_file->flags & > > + if (!ring_buffer_time_stamp_abs(*current_rb) && (trace_file->flags & > > (EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) && > > (entry = this_cpu_read(trace_buffered_event))) { > > /* Try to use the per cpu buffer first */ > > @@ -6079,6 +6079,29 @@ static int tracing_clock_open(struct inode *inode, > > struct file *file) > > return ret; > > } > > > > +int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs) > > +{ > > + mutex_lock(&trace_types_lock); > > + > > + ring_buffer_set_time_stamp_abs(tr->trace_buffer.buffer, abs); > > + > > + /* > > + * New timestamps may not be consistent with the previous setting. > > + * Reset the buffer so that it doesn't have incomparable timestamps. > > + */ > > + tracing_reset_online_cpus(&tr->trace_buffer); > > + > > +#ifdef CONFIG_TRACER_MAX_TRACE > > + if (tr->flags & TRACE_ARRAY_FL_GLOBAL && tr->max_buffer.buffer) > > + ring_buffer_set_time_stamp_abs(tr->max_buffer.buffer, abs); > > + tracing_reset_online_cpus(&tr->max_buffer); > > Why do you do this only for the global array? AFAIK instance arrays > can have the max buffer too. Am I missing something? >
Yes, I think you're right. Will take a closer look and change as needed. Thanks, Tom
