diff options
| author | Steven Rostedt <srostedt@redhat.com> | 2009-09-03 10:12:13 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2009-09-04 11:25:27 -0400 |
| commit | 1b959e18c4d6b4b981f887260b0f8e7939efa411 (patch) | |
| tree | 3f7b9950cfe19742cfe04bc3feb11f7ad0a46e71 /kernel/trace/ring_buffer.c | |
| parent | 98277991a99734f3a31d638afb47d4484ac73e43 (diff) | |
| download | lwn-1b959e18c4d6b4b981f887260b0f8e7939efa411.tar.gz lwn-1b959e18c4d6b4b981f887260b0f8e7939efa411.zip | |
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>
Diffstat (limited to 'kernel/trace/ring_buffer.c')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 16 |
1 files changed, 4 insertions, 12 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 2878bd43a59c..a05541a8fbae 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -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; } |