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,URIBL_BLOCKED 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 B4FBFC433E2 for ; Mon, 1 Jun 2020 08:44:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9396820734 for ; Mon, 1 Jun 2020 08:44:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591001073; bh=++2cB/ePJhne1YRp0fru1zBYoji5d1nprT5N9O4udpk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=GefiVBLfOOxgEgPOjLnrH2SOvLQ8dgDOMMTsdyJ2T2/wL6zn5DcFfK96JKqR6eWR3 p5GKB53P4xJT4FzFpe7lb2wLEsSLm9WJciAII3W+tP+iEUeg1G9bWOtvBTcyCjJrsi gJfgl+E6y5y4kmOjQ7X4ItoCnLBcDPAQoUJ877Og= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728269AbgFAIoa (ORCPT ); Mon, 1 Jun 2020 04:44:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:38832 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726142AbgFAIo3 (ORCPT ); Mon, 1 Jun 2020 04:44:29 -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 B0D94206E2; Mon, 1 Jun 2020 08:44:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591001068; bh=++2cB/ePJhne1YRp0fru1zBYoji5d1nprT5N9O4udpk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wVfow37nJUctQuczEjtuvdKVbO338MPrWmtxn6qzZZHMLNELwOQlIvzJoFUuF/1kq q5DWi1Wf0naUXbCdA1uSgSP2CWJRK7dS8k1Y+Djaw8xRkHX+tVonEUHstDVdezlly+ CKUb/UU3oTLuSzgUFnUcgt1pHUYemwJpSNjNMHJk= Date: Mon, 1 Jun 2020 10:44:26 +0200 From: Greg KH To: Tao pilgrim Cc: Jens Axboe , hch@lst.de, 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: <20200601084426.GB1667318@kroah.com> References: <20200529141100.37519-1-pilgrimtao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, Jun 01, 2020 at 03:22:01PM +0800, Tao pilgrim wrote: > On Fri, May 29, 2020 at 10:13 PM Jens Axboe wrote: > > > > On 5/29/20 8:11 AM, Kaitao Cheng wrote: > > > There is a function named ilog2() exist which can replace blksize. > > > The generated code will be shorter and more efficient on some > > > architecture, such as arm64. And ilog2() can be optimized according > > > to different architecture. > > > > When you posted this last time, I said: > > > > "I like the simplification, but do you have any results to back up > > that claim? Is the generated code shorter? Runs faster?" > > > > Hi Jens Axboe: > > I did a test on ARM64. > unsigned int ckt_blksize(int size) > { > return blksize_bits(size); > } > unsigned int ckt_ilog2(int size) > { > return ilog2(size); > } > > When I compiled it into assembly code, I got the following result, > > 0000000000000088 : > 88: 2a0003e8 mov w8, w0 > 8c: 321d03e0 orr w0, wzr, #0x8 > 90: 11000400 add w0, w0, #0x1 > 94: 7108051f cmp w8, #0x201 > 98: 53017d08 lsr w8, w8, #1 > 9c: 54ffffa8 b.hi 90 > a0: d65f03c0 ret > a4: d503201f nop > > 00000000000000a8 : > a8: 320013e8 orr w8, wzr, #0x1f > ac: 5ac01009 clz w9, w0 > b0: 4b090108 sub w8, w8, w9 > b4: 7100001f cmp w0, #0x0 > b8: 5a9f1100 csinv w0, w8, wzr, ne > bc: d65f03c0 ret > > The generated code of ilog2 is shorter , and runs faster But does this code path actually show up anywhere that is actually measurable as mattering? If so, please show that benchmark results. thanks, greg k-h 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 42668C433E0 for ; Mon, 1 Jun 2020 15:03:10 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 13EE82065C for ; Mon, 1 Jun 2020 15:03:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="fjdNmxFR"; 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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jflxq-0003iQ-3b; Mon, 01 Jun 2020 15:02:58 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jfg3b-0000nY-56 for linux-nvme@lists.infradead.org; Mon, 01 Jun 2020 08:44:32 +0000 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 B0D94206E2; Mon, 1 Jun 2020 08:44:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591001068; bh=++2cB/ePJhne1YRp0fru1zBYoji5d1nprT5N9O4udpk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wVfow37nJUctQuczEjtuvdKVbO338MPrWmtxn6qzZZHMLNELwOQlIvzJoFUuF/1kq q5DWi1Wf0naUXbCdA1uSgSP2CWJRK7dS8k1Y+Djaw8xRkHX+tVonEUHstDVdezlly+ CKUb/UU3oTLuSzgUFnUcgt1pHUYemwJpSNjNMHJk= Date: Mon, 1 Jun 2020 10:44:26 +0200 From: Greg KH To: Tao pilgrim Subject: Re: [PATCH v2] blkdev: Replace blksize_bits() with ilog2() Message-ID: <20200601084426.GB1667318@kroah.com> References: <20200529141100.37519-1-pilgrimtao@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200601_014431_214856_0068BCE0 X-CRM114-Status: GOOD ( 15.52 ) X-Mailman-Approved-At: Mon, 01 Jun 2020 08:02:54 -0700 X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: hoeppner@linux.ibm.com, heiko.carstens@de.ibm.com, linux-nvme@lists.infradead.org, dhowells@redhat.com, clm@fb.com, deepa.kernel@gmail.com, houtao1@huawei.com, hch@lst.de, linux-s390@vger.kernel.org, bvanassche@acm.org, darrick.wong@oracle.com, Mark Fasheh , satyat@google.com, hch@infradead.org, borntraeger@de.ibm.com, gor@linux.ibm.com, ajay.joshi@wdc.com, chaitanya.kulkarni@wdc.com, chao@kernel.org, Josef Bacik , ming.lei@redhat.com, viro@zeniv.linux.org.uk, Muchun Song , dsterba@suse.com, jaegeuk@kernel.org, jlbec@evilplan.org, sagi@grimberg.me, Jens Axboe , balbi@kernel.org, damien.lemoal@wdc.com, martin.petersen@oracle.com, joseph.qi@linux.alibaba.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, asml.silence@gmail.com, linux-btrfs@vger.kernel.org, sth@linux.ibm.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, Jun 01, 2020 at 03:22:01PM +0800, Tao pilgrim wrote: > On Fri, May 29, 2020 at 10:13 PM Jens Axboe wrote: > > > > On 5/29/20 8:11 AM, Kaitao Cheng wrote: > > > There is a function named ilog2() exist which can replace blksize. > > > The generated code will be shorter and more efficient on some > > > architecture, such as arm64. And ilog2() can be optimized according > > > to different architecture. > > > > When you posted this last time, I said: > > > > "I like the simplification, but do you have any results to back up > > that claim? Is the generated code shorter? Runs faster?" > > > > Hi Jens Axboe: > > I did a test on ARM64. > unsigned int ckt_blksize(int size) > { > return blksize_bits(size); > } > unsigned int ckt_ilog2(int size) > { > return ilog2(size); > } > > When I compiled it into assembly code, I got the following result, > > 0000000000000088 : > 88: 2a0003e8 mov w8, w0 > 8c: 321d03e0 orr w0, wzr, #0x8 > 90: 11000400 add w0, w0, #0x1 > 94: 7108051f cmp w8, #0x201 > 98: 53017d08 lsr w8, w8, #1 > 9c: 54ffffa8 b.hi 90 > a0: d65f03c0 ret > a4: d503201f nop > > 00000000000000a8 : > a8: 320013e8 orr w8, wzr, #0x1f > ac: 5ac01009 clz w9, w0 > b0: 4b090108 sub w8, w8, w9 > b4: 7100001f cmp w0, #0x0 > b8: 5a9f1100 csinv w0, w8, wzr, ne > bc: d65f03c0 ret > > The generated code of ilog2 is shorter , and runs faster But does this code path actually show up anywhere that is actually measurable as mattering? If so, please show that benchmark results. thanks, greg k-h _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Date: Mon, 1 Jun 2020 10:44:26 +0200 Subject: [Ocfs2-devel] [PATCH v2] blkdev: Replace blksize_bits() with ilog2() In-Reply-To: References: <20200529141100.37519-1-pilgrimtao@gmail.com> Message-ID: <20200601084426.GB1667318@kroah.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tao pilgrim Cc: Jens Axboe , hch@lst.de, 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 On Mon, Jun 01, 2020 at 03:22:01PM +0800, Tao pilgrim wrote: > On Fri, May 29, 2020 at 10:13 PM Jens Axboe wrote: > > > > On 5/29/20 8:11 AM, Kaitao Cheng wrote: > > > There is a function named ilog2() exist which can replace blksize. > > > The generated code will be shorter and more efficient on some > > > architecture, such as arm64. And ilog2() can be optimized according > > > to different architecture. > > > > When you posted this last time, I said: > > > > "I like the simplification, but do you have any results to back up > > that claim? Is the generated code shorter? Runs faster?" > > > > Hi Jens Axboe: > > I did a test on ARM64. > unsigned int ckt_blksize(int size) > { > return blksize_bits(size); > } > unsigned int ckt_ilog2(int size) > { > return ilog2(size); > } > > When I compiled it into assembly code, I got the following result, > > 0000000000000088 : > 88: 2a0003e8 mov w8, w0 > 8c: 321d03e0 orr w0, wzr, #0x8 > 90: 11000400 add w0, w0, #0x1 > 94: 7108051f cmp w8, #0x201 > 98: 53017d08 lsr w8, w8, #1 > 9c: 54ffffa8 b.hi 90 > a0: d65f03c0 ret > a4: d503201f nop > > 00000000000000a8 : > a8: 320013e8 orr w8, wzr, #0x1f > ac: 5ac01009 clz w9, w0 > b0: 4b090108 sub w8, w8, w9 > b4: 7100001f cmp w0, #0x0 > b8: 5a9f1100 csinv w0, w8, wzr, ne > bc: d65f03c0 ret > > The generated code of ilog2 is shorter , and runs faster But does this code path actually show up anywhere that is actually measurable as mattering? If so, please show that benchmark results. thanks, greg k-h 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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 B83BEC433DF for ; Mon, 1 Jun 2020 08:44:50 +0000 (UTC) Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8017B206E2 for ; Mon, 1 Jun 2020 08:44:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sourceforge.net header.i=@sourceforge.net header.b="RrzgWRJZ"; 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bh=LUeDKl9lu4Ts/3E6O2r0fpaff2XnrGzDNWCZFZrIToY=; b=PQ8eTfOl5I8/VzCPge8yncXO+y 8EpbZyHHuaIqc5X6Gybfv5W5S2lOu2ZacDQcodqzz5ho4oDKMoR82UoxL4ka6QFRPM10dbb6BO1Kq KTXs6qLTEzhg2S761T05s1Ha3mQtVVIce0g4/xF9pIlGnlbeDrJ2i3YgPRifS6PD0BQ8=; Received: from mail.kernel.org ([198.145.29.99]) by sfi-mx-4.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92.2) id 1jfg3k-006MCS-Td for linux-f2fs-devel@lists.sourceforge.net; Mon, 01 Jun 2020 08:44:46 +0000 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 B0D94206E2; Mon, 1 Jun 2020 08:44:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591001068; bh=++2cB/ePJhne1YRp0fru1zBYoji5d1nprT5N9O4udpk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wVfow37nJUctQuczEjtuvdKVbO338MPrWmtxn6qzZZHMLNELwOQlIvzJoFUuF/1kq q5DWi1Wf0naUXbCdA1uSgSP2CWJRK7dS8k1Y+Djaw8xRkHX+tVonEUHstDVdezlly+ CKUb/UU3oTLuSzgUFnUcgt1pHUYemwJpSNjNMHJk= Date: Mon, 1 Jun 2020 10:44:26 +0200 From: Greg KH To: Tao pilgrim Message-ID: <20200601084426.GB1667318@kroah.com> References: <20200529141100.37519-1-pilgrimtao@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Headers-End: 1jfg3k-006MCS-Td Subject: Re: [f2fs-dev] [PATCH v2] blkdev: Replace blksize_bits() with ilog2() X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: hoeppner@linux.ibm.com, heiko.carstens@de.ibm.com, linux-nvme@lists.infradead.org, dhowells@redhat.com, clm@fb.com, deepa.kernel@gmail.com, houtao1@huawei.com, hch@lst.de, linux-s390@vger.kernel.org, bvanassche@acm.org, darrick.wong@oracle.com, Mark Fasheh , satyat@google.com, hch@infradead.org, borntraeger@de.ibm.com, gor@linux.ibm.com, chaitanya.kulkarni@wdc.com, Josef Bacik , ming.lei@redhat.com, viro@zeniv.linux.org.uk, Muchun Song , dsterba@suse.com, jaegeuk@kernel.org, jlbec@evilplan.org, sagi@grimberg.me, Jens Axboe , balbi@kernel.org, damien.lemoal@wdc.com, martin.petersen@oracle.com, joseph.qi@linux.alibaba.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, asml.silence@gmail.com, linux-btrfs@vger.kernel.org, sth@linux.ibm.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Mon, Jun 01, 2020 at 03:22:01PM +0800, Tao pilgrim wrote: > On Fri, May 29, 2020 at 10:13 PM Jens Axboe wrote: > > > > On 5/29/20 8:11 AM, Kaitao Cheng wrote: > > > There is a function named ilog2() exist which can replace blksize. > > > The generated code will be shorter and more efficient on some > > > architecture, such as arm64. And ilog2() can be optimized according > > > to different architecture. > > > > When you posted this last time, I said: > > > > "I like the simplification, but do you have any results to back up > > that claim? Is the generated code shorter? Runs faster?" > > > > Hi Jens Axboe: > > I did a test on ARM64. > unsigned int ckt_blksize(int size) > { > return blksize_bits(size); > } > unsigned int ckt_ilog2(int size) > { > return ilog2(size); > } > > When I compiled it into assembly code, I got the following result, > > 0000000000000088 : > 88: 2a0003e8 mov w8, w0 > 8c: 321d03e0 orr w0, wzr, #0x8 > 90: 11000400 add w0, w0, #0x1 > 94: 7108051f cmp w8, #0x201 > 98: 53017d08 lsr w8, w8, #1 > 9c: 54ffffa8 b.hi 90 > a0: d65f03c0 ret > a4: d503201f nop > > 00000000000000a8 : > a8: 320013e8 orr w8, wzr, #0x1f > ac: 5ac01009 clz w9, w0 > b0: 4b090108 sub w8, w8, w9 > b4: 7100001f cmp w0, #0x0 > b8: 5a9f1100 csinv w0, w8, wzr, ne > bc: d65f03c0 ret > > The generated code of ilog2 is shorter , and runs faster But does this code path actually show up anywhere that is actually measurable as mattering? If so, please show that benchmark results. thanks, greg k-h _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel