From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 826CCC433E1 for ; Thu, 2 Jul 2020 21:58:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B91220780 for ; Thu, 2 Jul 2020 21:58:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726368AbgGBV6h (ORCPT ); Thu, 2 Jul 2020 17:58:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:52978 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726305AbgGBV6f (ORCPT ); Thu, 2 Jul 2020 17:58:35 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D1CCD21BE5; Thu, 2 Jul 2020 21:58:34 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.93) (envelope-from ) id 1jr7E1-004Bk5-MA; Thu, 02 Jul 2020 17:58:33 -0400 Message-ID: <20200702215833.563578523@goodmis.org> User-Agent: quilt/0.66 Date: Thu, 02 Jul 2020 17:58:26 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Mathieu Desnoyers Subject: [for-next][PATCH 14/18] ring-buffer: Mark the !tail (crossing a page) as unlikely References: <20200702215812.428188663@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" It is the uncommon case where an event crosses a sub buffer boundary (page) mark that check at the end of reserving an event as unlikely. Suggested-by: Mathieu Desnoyers Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index ed1941304f69..888bc9177937 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -3260,7 +3260,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, * If this is the first commit on the page, then update * its timestamp. */ - if (!tail) + if (unlikely(!tail)) tail_page->page->time_stamp = info->ts; /* account for these added bytes */ -- 2.26.2