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Commit 1b959e18 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
Browse files

ring-buffer: remove unnecessary cpu_relax 



The loops in the ring buffer that use cpu_relax are not dependent on
other CPUs. They simply came across some padding in the ring buffer and
are skipping over them. It is a normal loop and does not require a
cpu_relax.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 98277991

kernel/trace/ring_buffer.c

+4 −12
Original line number Diff line number Diff line
@@ -3132,10 +3132,8 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) 
		spin_unlock(&cpu_buffer->reader_lock);

	local_irq_restore(flags);



	if (event && event->type_len == RINGBUF_TYPE_PADDING) {

		cpu_relax();

	if (event && event->type_len == RINGBUF_TYPE_PADDING)

		goto again;

	}



	return event;

}
@@ -3160,10 +3158,8 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) 
	event = rb_iter_peek(iter, ts);

	spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);



	if (event && event->type_len == RINGBUF_TYPE_PADDING) {

		cpu_relax();

	if (event && event->type_len == RINGBUF_TYPE_PADDING)

		goto again;

	}



	return event;

}
@@ -3209,10 +3205,8 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) 
 out:

	preempt_enable();



	if (event && event->type_len == RINGBUF_TYPE_PADDING) {

		cpu_relax();

	if (event && event->type_len == RINGBUF_TYPE_PADDING)

		goto again;

	}



	return event;

}
@@ -3302,10 +3296,8 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) 
 out:

	spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);



	if (event && event->type_len == RINGBUF_TYPE_PADDING) {

		cpu_relax();

	if (event && event->type_len == RINGBUF_TYPE_PADDING)

		goto again;

	}



	return event;

}