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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,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 7282EC433EF for ; Mon, 13 Sep 2021 11:19:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 490EE610A6 for ; Mon, 13 Sep 2021 11:19:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239496AbhIMLUg (ORCPT ); Mon, 13 Sep 2021 07:20:36 -0400 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:46743 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239485AbhIMLUf (ORCPT ); Mon, 13 Sep 2021 07:20:35 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R521e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=hsiangkao@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0UoCWglD_1631531956; Received: from B-P7TQMD6M-0146.local(mailfrom:hsiangkao@linux.alibaba.com fp:SMTPD_---0UoCWglD_1631531956) by smtp.aliyun-inc.com(127.0.0.1); Mon, 13 Sep 2021 19:19:18 +0800 Date: Mon, 13 Sep 2021 19:19:16 +0800 From: Gao Xiang To: Yue Hu Cc: Yue Hu , xiang@kernel.org, chao@kernel.org, linux-erofs@lists.ozlabs.org, linux-kernel@vger.kernel.org, huyue2@yulong.com, zhangwen@yulong.com Subject: Re: [PATCH] erofs: fix compacted_{4b_initial, 2b} when compacted_4b_initial > totalidx Message-ID: References: <20210913072405.1128-1-zbestahu@gmail.com> <20210913170016.00007580.zbestahu@gmail.com> <20210913185836.088e7059.zbestahu@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210913185836.088e7059.zbestahu@163.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Yue, On Mon, Sep 13, 2021 at 06:58:36PM +0800, Yue Hu wrote: > Hi Xiang, > > On Mon, 13 Sep 2021 17:11:24 +0800 > Gao Xiang wrote: > > > On Mon, Sep 13, 2021 at 05:00:16PM +0800, Yue Hu wrote: > > > On Mon, 13 Sep 2021 16:48:45 +0800 > > > Gao Xiang wrote: > > > > > > > Hi Yue, > > > > > > > > On Mon, Sep 13, 2021 at 03:24:05PM +0800, Yue Hu wrote: > > > > > From: Yue Hu > > > > > > > > > > mkfs.erofs will treat compacted_4b_initial & compacted_2b as 0 if > > > > > compacted_4b_initial > totalidx, kernel should be aligned with it > > > > > accordingly. > > > > > > > > There is no difference between compacted_4b_initial or compacted_4b_end > > > > for compacted 4B. Since in this way totalidx for compact 2B won't larger > > > > than 16 (number of lclusters in a compacted 2B pack.) > > > > > > However, we can see compacted_2b is a big number for this case. It should > > > be pointless. > > > > Does it has some real impact? > > No real impact to correct result. > > > > > compacted_4b_initial is only used for the alignment use for the > > first compacted_2b so that each compacted_2b pack won't cross > > the block (page) boundary. And compacted_4b_end is for the last > > lclusters aren't fitted in any compacted_2b pack. > > > > If compacted_4b_initial > totalidx, I think the whole indexes > > would be compacted 4B and handled in > > > > if (lcn < compacted_4b_initial) { > > amortizedshift = 2; > > goto out; > > } > > Yes, it is. > > My point is why we need compacted_2b here for this case. If it's > not helpful/used for next code logic, we should remove/avoid it. > I think that may cause some misunderstanding and consume unneeded > CPU resources. Okay, make sense. If the number of compacted_2b misleads, how about just if ((vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) && compacted_4b_initial <= totalidx) { compacted_2b = ...; } else { compacted_2b = 0; } , and refine the commit message to point out the following facts for other folks: - compacted_4b_initial is used contain the very first lclusters in order to fulfill the alignment of the first compacted_2b pack; - compacted_4b_end is used for the last lclusters which aren't fitted in the previous compacted_2b packs; - if compacted_4b_initial > totalidx, the whole indexes will be compacted 4B and handled with compacted_4b_initial. Thanks, Gao Xiang > > Thanks. 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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,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 E0E1FC433F5 for ; Mon, 13 Sep 2021 11:19:46 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 28AA461051 for ; Mon, 13 Sep 2021 11:19:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 28AA461051 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4H7PC45ntBz2yKN for ; Mon, 13 Sep 2021 21:19:44 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.alibaba.com (client-ip=115.124.30.42; helo=out30-42.freemail.mail.aliyun.com; envelope-from=hsiangkao@linux.alibaba.com; receiver=) Received: from out30-42.freemail.mail.aliyun.com (out30-42.freemail.mail.aliyun.com [115.124.30.42]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4H7PBz48bJz2xr8 for ; Mon, 13 Sep 2021 21:19:35 +1000 (AEST) X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R521e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04426; MF=hsiangkao@linux.alibaba.com; NM=1; PH=DS; RN=8; SR=0; TI=SMTPD_---0UoCWglD_1631531956; Received: from B-P7TQMD6M-0146.local(mailfrom:hsiangkao@linux.alibaba.com fp:SMTPD_---0UoCWglD_1631531956) by smtp.aliyun-inc.com(127.0.0.1); Mon, 13 Sep 2021 19:19:18 +0800 Date: Mon, 13 Sep 2021 19:19:16 +0800 From: Gao Xiang To: Yue Hu Subject: Re: [PATCH] erofs: fix compacted_{4b_initial, 2b} when compacted_4b_initial > totalidx Message-ID: References: <20210913072405.1128-1-zbestahu@gmail.com> <20210913170016.00007580.zbestahu@gmail.com> <20210913185836.088e7059.zbestahu@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210913185836.088e7059.zbestahu@163.com> X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, huyue2@yulong.com, linux-erofs@lists.ozlabs.org, zhangwen@yulong.com Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" Hi Yue, On Mon, Sep 13, 2021 at 06:58:36PM +0800, Yue Hu wrote: > Hi Xiang, > > On Mon, 13 Sep 2021 17:11:24 +0800 > Gao Xiang wrote: > > > On Mon, Sep 13, 2021 at 05:00:16PM +0800, Yue Hu wrote: > > > On Mon, 13 Sep 2021 16:48:45 +0800 > > > Gao Xiang wrote: > > > > > > > Hi Yue, > > > > > > > > On Mon, Sep 13, 2021 at 03:24:05PM +0800, Yue Hu wrote: > > > > > From: Yue Hu > > > > > > > > > > mkfs.erofs will treat compacted_4b_initial & compacted_2b as 0 if > > > > > compacted_4b_initial > totalidx, kernel should be aligned with it > > > > > accordingly. > > > > > > > > There is no difference between compacted_4b_initial or compacted_4b_end > > > > for compacted 4B. Since in this way totalidx for compact 2B won't larger > > > > than 16 (number of lclusters in a compacted 2B pack.) > > > > > > However, we can see compacted_2b is a big number for this case. It should > > > be pointless. > > > > Does it has some real impact? > > No real impact to correct result. > > > > > compacted_4b_initial is only used for the alignment use for the > > first compacted_2b so that each compacted_2b pack won't cross > > the block (page) boundary. And compacted_4b_end is for the last > > lclusters aren't fitted in any compacted_2b pack. > > > > If compacted_4b_initial > totalidx, I think the whole indexes > > would be compacted 4B and handled in > > > > if (lcn < compacted_4b_initial) { > > amortizedshift = 2; > > goto out; > > } > > Yes, it is. > > My point is why we need compacted_2b here for this case. If it's > not helpful/used for next code logic, we should remove/avoid it. > I think that may cause some misunderstanding and consume unneeded > CPU resources. Okay, make sense. If the number of compacted_2b misleads, how about just if ((vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) && compacted_4b_initial <= totalidx) { compacted_2b = ...; } else { compacted_2b = 0; } , and refine the commit message to point out the following facts for other folks: - compacted_4b_initial is used contain the very first lclusters in order to fulfill the alignment of the first compacted_2b pack; - compacted_4b_end is used for the last lclusters which aren't fitted in the previous compacted_2b packs; - if compacted_4b_initial > totalidx, the whole indexes will be compacted 4B and handled with compacted_4b_initial. Thanks, Gao Xiang > > Thanks.