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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 91AF5C433DF for ; Tue, 2 Jun 2020 06:13:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5D48F20738 for ; Tue, 2 Jun 2020 06:13:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591078390; bh=rRykBBWnGs96WxsrQLDxmACWOa/UFVBVpsVgwWsmVXk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=jS0zbsLx8WjyJa9XR7p/dpVxbjJUqKTXfMEq+2CPZ7znaKKzXOK2tiR/PVzh58M6i 3+cgfJRFMnMZ2YQTjiMcd8V9JuoZncOEMfSO5zcJNgyegTsoq8lboJlznlixQI2h9j pumPxYKn2JOtjr1I6MD7jI3vVMVi49vbhP1LA9xA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726181AbgFBGNJ (ORCPT ); Tue, 2 Jun 2020 02:13:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:48836 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725616AbgFBGNJ (ORCPT ); Tue, 2 Jun 2020 02:13:09 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 A38F5206A2; Tue, 2 Jun 2020 06:13:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591078388; bh=rRykBBWnGs96WxsrQLDxmACWOa/UFVBVpsVgwWsmVXk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1Hjjl6n79wTkMOGwUGwEfwwZ3SrDwiog0vc+onIjwGGuMKSzKjJvPZlMTPoeBSV3T s00gQNv4yH6M7lX9kvpeFeAHUFFI/guixhK0D6JH5aXOm+zA8naHv9mb1MQJ2Wi8AE gcQr/P3/ruI6VfcDbwA53bx45o8NZmrvKj7Cj1H8= Date: Tue, 2 Jun 2020 08:13:05 +0200 From: Greg KH To: Christoph Hellwig Cc: Tao pilgrim , Jens Axboe , sth@linux.ibm.com, viro@zeniv.linux.org.uk, clm@fb.com, jaegeuk@kernel.org, hch@infradead.org, Mark Fasheh , dhowells@redhat.com, balbi@kernel.org, damien.lemoal@wdc.com, bvanassche@acm.org, ming.lei@redhat.com, martin.petersen@oracle.com, satyat@google.com, chaitanya.kulkarni@wdc.com, houtao1@huawei.com, asml.silence@gmail.com, ajay.joshi@wdc.com, linux-kernel@vger.kernel.org, Muchun Song , hoeppner@linux.ibm.com, heiko.carstens@de.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, linux-s390@vger.kernel.org, sagi@grimberg.me, linux-nvme@lists.infradead.org, linux-usb@vger.kernel.org, Josef Bacik , dsterba@suse.com, linux-btrfs@vger.kernel.org, chao@kernel.org, linux-f2fs-devel@lists.sourceforge.net, darrick.wong@oracle.com, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, jlbec@evilplan.org, joseph.qi@linux.alibaba.com, ocfs2-devel@oss.oracle.com, deepa.kernel@gmail.com Subject: Re: [PATCH v2] blkdev: Replace blksize_bits() with ilog2() Message-ID: <20200602061305.GA2258861@kroah.com> References: <20200529141100.37519-1-pilgrimtao@gmail.com> <20200601084426.GB1667318@kroah.com> <20200602055152.GA11620@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200602055152.GA11620@lst.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 02, 2020 at 07:51:52AM +0200, Christoph Hellwig wrote: > On Mon, Jun 01, 2020 at 10:44:26AM +0200, Greg KH wrote: > > But does this code path actually show up anywhere that is actually > > measurable as mattering? > > > > If so, please show that benchmark results. > > I think the requests are starting to be a bit unreasonable. Tao is > replacing a reimplementation of a standard function with that standard > function / compiler builtin. We don't put such a high burden on that. That's fine, but to say it is "faster" usually means we want to see it actually going faster somehow :) > And once the proper existing fields are used where possible as shown > in my reply just replacing the rest seems totally obvious - quite > contrary I think keeping a reimplementation would need a high bar. Your patch makes sense, I was not objecting to that. thanks, greg k-h