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Commit 00b41452 authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt (VMware)
Browse files

ring-buffer: Add interface for setting absolute time stamps 

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.

Only the interface is added here; a subsequent patch will add the
underlying implementation.

Link: http://lkml.kernel.org/r/ce96119de44c7fe0ee44786d15254e9b493040d3.1516069914.git.tom.zanussi@linux.intel.com



Signed-off-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: default avatarBaohong Liu <baohong.liu@intel.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent c193707d

include/linux/ring_buffer.h

+2 −0
Original line number Diff line number Diff line
@@ -178,6 +178,8 @@ 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);

kernel/trace/ring_buffer.c

+11 −0
Original line number Diff line number Diff line
@@ -488,6 +488,7 @@ struct ring_buffer { 
	u64				(*clock)(void);



	struct rb_irq_work		irq_work;

	bool				time_stamp_abs;

};



struct ring_buffer_iter {
@@ -1382,6 +1383,16 @@ 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)

kernel/trace/trace.c

+32 −1
Original line number Diff line number Diff line
@@ -2269,7 +2269,7 @@ trace_event_buffer_lock_reserve(struct ring_buffer **current_rb, 


	*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 */
@@ -6282,6 +6282,37 @@ 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)

{

	int ret = 0;



	mutex_lock(&trace_types_lock);



	if (abs && tr->time_stamp_abs_ref++)

		goto out;



	if (!abs) {

		if (WARN_ON_ONCE(!tr->time_stamp_abs_ref)) {

			ret = -EINVAL;

			goto out;

		}



		if (--tr->time_stamp_abs_ref)

			goto out;

	}



	ring_buffer_set_time_stamp_abs(tr->trace_buffer.buffer, abs);



#ifdef CONFIG_TRACER_MAX_TRACE

	if (tr->max_buffer.buffer)

		ring_buffer_set_time_stamp_abs(tr->max_buffer.buffer, abs);

#endif

 out:

	mutex_unlock(&trace_types_lock);



	return ret;

}



struct ftrace_buffer_info {

	struct trace_iterator	iter;

	void			*spare;

kernel/trace/trace.h

+3 −0
Original line number Diff line number Diff line
@@ -273,6 +273,7 @@ struct trace_array { 
	/* function tracing enabled */

	int			function_enabled;

#endif

	int			time_stamp_abs_ref;

};



enum {
@@ -286,6 +287,8 @@ extern struct mutex trace_types_lock; 
extern int trace_array_get(struct trace_array *tr);

extern void trace_array_put(struct trace_array *tr);



extern int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs);



/*

 * The global tracer (top) should be the first trace array added,

 * but we check the flag anyway.