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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: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2009-09-03 10:12:13 -04:00 committed by Steven Rostedt
parent 98277991a9
commit 1b959e18c4
1 changed files with 4 additions and 12 deletions
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16
kernel/trace/ring_buffer.c
View File

@ -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;
}