From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934402AbZIEADG (ORCPT ); Fri, 4 Sep 2009 20:03:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934149AbZIEABX (ORCPT ); Fri, 4 Sep 2009 20:01:23 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:33506 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934002AbZIEABT (ORCPT ); Fri, 4 Sep 2009 20:01:19 -0400 Message-Id: <20090905000121.298060241@goodmis.org> References: <20090904235527.520961911@goodmis.org> User-Agent: quilt/0.46-1 Date: Fri, 04 Sep 2009 19:55:30 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker , Arnaldo Carvalho de Melo Subject: [PATCH 03/18] ring-buffer: remove unnecessary cpu_relax Content-Disposition: inline; filename=0003-ring-buffer-remove-unnecessary-cpu_relax.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt 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 --- 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 2878bd4..a05541a 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; } -- 1.6.3.3 --