From: Yue Hu <zbestahu@163.com> To: Gao Xiang <hsiangkao@linux.alibaba.com> Cc: Yue Hu <zbestahu@gmail.com>, 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 Date: Mon, 13 Sep 2021 20:22:58 +0800 [thread overview] Message-ID: <20210913202258.356ba284.zbestahu@163.com> (raw) In-Reply-To: <YT8ztN/F4StUYYNS@B-P7TQMD6M-0146.local> On Mon, 13 Sep 2021 19:19:16 +0800 Gao Xiang <hsiangkao@linux.alibaba.com> wrote: > 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 <hsiangkao@linux.alibaba.com> 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 <hsiangkao@linux.alibaba.com> wrote: > > > > > > > > > Hi Yue, > > > > > > > > > > On Mon, Sep 13, 2021 at 03:24:05PM +0800, Yue Hu wrote: > > > > > > From: Yue Hu <huyue2@yulong.com> > > > > > > > > > > > > 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; > } Looks good. So, the patch title may change a little. > > , 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. Ok, will add these facts above in v2. Thanks. > > Thanks, > Gao Xiang > > > > > Thanks.
WARNING: multiple messages have this Message-ID (diff)
From: Yue Hu <zbestahu@163.com> To: Gao Xiang <hsiangkao@linux.alibaba.com> Cc: linux-kernel@vger.kernel.org, huyue2@yulong.com, linux-erofs@lists.ozlabs.org, zhangwen@yulong.com Subject: Re: [PATCH] erofs: fix compacted_{4b_initial, 2b} when compacted_4b_initial > totalidx Date: Mon, 13 Sep 2021 20:22:58 +0800 [thread overview] Message-ID: <20210913202258.356ba284.zbestahu@163.com> (raw) In-Reply-To: <YT8ztN/F4StUYYNS@B-P7TQMD6M-0146.local> On Mon, 13 Sep 2021 19:19:16 +0800 Gao Xiang <hsiangkao@linux.alibaba.com> wrote: > 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 <hsiangkao@linux.alibaba.com> 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 <hsiangkao@linux.alibaba.com> wrote: > > > > > > > > > Hi Yue, > > > > > > > > > > On Mon, Sep 13, 2021 at 03:24:05PM +0800, Yue Hu wrote: > > > > > > From: Yue Hu <huyue2@yulong.com> > > > > > > > > > > > > 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; > } Looks good. So, the patch title may change a little. > > , 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. Ok, will add these facts above in v2. Thanks. > > Thanks, > Gao Xiang > > > > > Thanks.
next prev parent reply other threads:[~2021-09-13 12:23 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-13 7:24 [PATCH] erofs: fix compacted_{4b_initial, 2b} when compacted_4b_initial > totalidx Yue Hu 2021-09-13 7:24 ` Yue Hu 2021-09-13 8:48 ` Gao Xiang 2021-09-13 8:48 ` Gao Xiang 2021-09-13 9:00 ` Yue Hu 2021-09-13 9:00 ` Yue Hu 2021-09-13 9:11 ` Gao Xiang 2021-09-13 9:11 ` Gao Xiang 2021-09-13 10:58 ` Yue Hu 2021-09-13 10:58 ` Yue Hu 2021-09-13 11:19 ` Gao Xiang 2021-09-13 11:19 ` Gao Xiang 2021-09-13 12:22 ` Yue Hu [this message] 2021-09-13 12:22 ` Yue Hu
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