Re: [PATCH] erofs: remove unneeded icur field from struct z_erofs_decompress_frontend
From: Yue Hu
Date: Mon Apr 17 2023 - 03:38:13 EST
On Mon, 17 Apr 2023 15:12:31 +0800
Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> wrote:
> On 2023/4/17 15:15, Yue Hu wrote:
> > On Mon, 17 Apr 2023 15:00:25 +0800
> > Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> wrote:
> >
>
> ..
>
> >>
> >> Although please help refine the comment below:
> >>
> >> /* scan & fill inplace I/O pages in the reverse order */
> >
> > Ok, will refine it in v2.
>
> I rethink this, I don't want to go far in this way, and this makes a
> O(n) scan into O(n^2) when a single inplace I/O page is added.
Yeah, i misread that, it should be global before submission, just ignore the change.
>
> So sorry, I don't think it's a good way, although I also don't think
> `icur` is a good name and we might need to find a better name.
>
> Thanks,
> Gao Xiang
>
> >
> >>
> >> Thanks,
> >> Gao Xiang
> >>
> >>>> + unsigned int icur = pcl->pclusterpages;
> >>>> - while (fe->icur > 0) {
> >>>> - if (!cmpxchg(&pcl->compressed_bvecs[--fe->icur].page,
> >>>> + while (icur > 0) {
> >>>> + if (!cmpxchg(&pcl->compressed_bvecs[--icur].page,
> >>>> NULL, bvec->page)) {
> >>>> - pcl->compressed_bvecs[fe->icur] = *bvec;
> >>>> + pcl->compressed_bvecs[icur] = *bvec;
> >>>> return true;
> >>>> }
> >>>> }
> >>>> @@ -877,8 +876,6 @@ static int z_erofs_collector_begin(struct z_erofs_decompress_frontend *fe)
> >>>> }
> >>>> z_erofs_bvec_iter_begin(&fe->biter, &fe->pcl->bvset,
> >>>> Z_EROFS_INLINE_BVECS, fe->pcl->vcnt);
> >>>> - /* since file-backed online pages are traversed in reverse order */
> >>>> - fe->icur = z_erofs_pclusterpages(fe->pcl);
> >>>> return 0;
> >>>> }