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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 90E1BC3A59F for ; Thu, 29 Aug 2019 09:31:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 12E0A2189D for ; Thu, 29 Aug 2019 09:31:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725782AbfH2JbV (ORCPT ); Thu, 29 Aug 2019 05:31:21 -0400 Received: from mail104.syd.optusnet.com.au ([211.29.132.246]:48653 "EHLO mail104.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725776AbfH2JbV (ORCPT ); Thu, 29 Aug 2019 05:31:21 -0400 Received: from dread.disaster.area (pa49-181-255-194.pa.nsw.optusnet.com.au [49.181.255.194]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id 56D2F43D073; Thu, 29 Aug 2019 19:31:19 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92) (envelope-from ) id 1i3Glx-0002di-RT; Thu, 29 Aug 2019 19:31:17 +1000 Date: Thu, 29 Aug 2019 19:31:17 +1000 From: Dave Chinner To: Christoph Hellwig Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH 4/5] xfs: speed up directory bestfree block scanning Message-ID: <20190829093117.GS1119@dread.disaster.area> References: <20190829063042.22902-1-david@fromorbit.com> <20190829063042.22902-5-david@fromorbit.com> <20190829082501.GA18614@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190829082501.GA18614@infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.2 cv=P6RKvmIu c=1 sm=1 tr=0 a=YO9NNpcXwc8z/SaoS+iAiA==:117 a=YO9NNpcXwc8z/SaoS+iAiA==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=FmdZ9Uzk2mMA:10 a=7-415B0cAAAA:8 a=d3U9ooY5FA7FCOP2F0UA:9 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, Aug 29, 2019 at 01:25:01AM -0700, Christoph Hellwig wrote: > Actually, another comment: > > > + /* Scan the free entry array for a large enough free space. */ > > + do { > > + if (be16_to_cpu(bests[findex]) != NULLDATAOFF && > > This could be changed to: > > if (bests[findex] != cpu_to_be16(NULLDATAOFF) && > > which might lead to slightly better code generation. I don't think it will make any difference because the very next comparison in the if() statement needs the cpu order bests[findex] value because its a >= check. Hence we have to calculate it anyway, and the compiler should be smart enough to only evaluate it once... Cheers, Dave. -- Dave Chinner david@fromorbit.com