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Commit ad964704 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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ring-buffer: Add stats field for amount read from trace ring buffer 



Add a stat about the number of events read from the ring buffer:

 #  cat /debug/tracing/per_cpu/cpu0/stats
entries: 39869
overrun: 870512
commit overrun: 0
bytes: 1449912
oldest event ts:  6561.368690
now ts:  6565.246426
dropped events: 0
read events: 112    <-- Added

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 03274a3f

include/linux/ring_buffer.h

+1 −0
Original line number Diff line number Diff line
@@ -167,6 +167,7 @@ unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu); 
unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);

unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);

unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);

unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);



u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);

void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,

kernel/trace/ring_buffer.c

+18 −0
Original line number Diff line number Diff line
@@ -3102,6 +3102,24 @@ ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu) 
}

EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu);



/**

 * ring_buffer_read_events_cpu - get the number of events successfully read

 * @buffer: The ring buffer

 * @cpu: The per CPU buffer to get the number of events read

 */

unsigned long

ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu)

{

	struct ring_buffer_per_cpu *cpu_buffer;



	if (!cpumask_test_cpu(cpu, buffer->cpumask))

		return 0;



	cpu_buffer = buffer->buffers[cpu];

	return cpu_buffer->read;

}

EXPORT_SYMBOL_GPL(ring_buffer_read_events_cpu);



/**

 * ring_buffer_entries - get the number of entries in a buffer

 * @buffer: The ring buffer

kernel/trace/trace.c

+3 −0
Original line number Diff line number Diff line
@@ -4430,6 +4430,9 @@ tracing_stats_read(struct file *filp, char __user *ubuf, 
	cnt = ring_buffer_dropped_events_cpu(tr->buffer, cpu);

	trace_seq_printf(s, "dropped events: %ld\n", cnt);



	cnt = ring_buffer_read_events_cpu(tr->buffer, cpu);

	trace_seq_printf(s, "read events: %ld\n", cnt);



	count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);



	kfree(s);