linux-kernel - Re: [f2fs-dev] [PATCH v6] f2fs: compress: support compress level

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Message-ID: <20201204032140.GD1963435@xiangao.remote.csb>
Date:   Fri, 4 Dec 2020 11:21:40 +0800
From:   Gao Xiang <hsiangkao@...hat.com>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     Eric Biggers <ebiggers@...nel.org>, jaegeuk@...nel.org,
        linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v6] f2fs: compress: support compress level

On Fri, Dec 04, 2020 at 11:11:03AM +0800, Chao Yu wrote:
> On 2020/12/4 10:47, Gao Xiang wrote:

...

> 
> > future (and add more dependency to algorithms, you might see BWT-based bzip2
> > removal patch
> 
> Oops, is that really allowed? I don't this is a good idea...and I don't see there
> are deletions from fs/ due to similar reason...

Fortunately, bzip is quite slow algorithm, so not affective at all.

My personal opinion based on compress algorithm principle (just for reference
as well...)
 - zlib should be better replaced with libdeflate if possible, the main point
   is that many hardware accelerator for deflate (LZ77 + huffman) are
   available;

 - lzo is not attractive from its format complexity and its CR/performance
    goal so lz4 is generally better due to its format design;

 - lzo-rle, oops, just introduced for zram I think, not sure quite helpful
   for file data (since anonymous pages are generally RLE-effective due to
   many repeative data.) But it'd be good if lzo author accepts it.

Thanks,
Gao Xiang

> 
> Thanks,
> > 
>