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Date:   Wed, 7 Mar 2018 11:12:52 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To:     Benjamin Warnke <4bwarnke@informatik.uni-hamburg.de>
Cc:     Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        linux-kernel@vger.kernel.org, herbert@gondor.apana.org.au,
        davem@davemloft.net, minchan@kernel.org, ngupta@vflare.org,
        sergey.senozhatsky.work@gmail.com
Subject: Re: [RESEND PATCH v3] crypto: add zBeWalgo compression for zram
Message-ID: <20180307021252.GA802@jagdpanzerIV>
References: <8CFBD60E-6A2B-4766-B6F9-09A98DEA26CB@informatik.uni-hamburg.de>
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Hello,

On (03/06/18 20:59), Benjamin Warnke wrote:
>    Currently ZRAM uses compression-algorithms from the crypto-api. ZRAM
>    compresses each page individually. As a result the compression algorithm
>    is
>    forced to use a very small sliding window. None of the available
>    compression
>    algorithms is designed to achieve high compression ratios with small
>    inputs.

I think you first need to merge zBeWalgo (looks like a long way to go)
And then add ZRAM support, as a separate patch.

>    - 'ecoham' (100 MiB) This dataset is one of the input files for the
>    scientific
>    application ECOHAM which runs an ocean simulation. This dataset contains a
>    lot of zeros. Where the data is not zero there are arrays of floating
>    point
>    values, adjacent float values are likely to be similar to each other,
>    allowing for high compression ratios.
> 
>    algorithm | ratio ??| compression ???| decompression
>    zbewalgo ?| ??12.94 | ?294.10 MBit/s | 1242.59 MBit/s
>    deflate ??| ??12.54 | ??75.51 MBit/s | ?736.39 MBit/s
>    842 ??????| ??12.26 | ?182.59 MBit/s | ?683.61 MBit/s
>    lz4hc ????| ??12.00 | ??51.23 MBit/s | 1524.73 MBit/s
>    lz4 ??????| ??10.68 | 1334.37 MBit/s | 1603.54 MBit/s
>    lzo ??????| ???9.79 | 1333.76 MBit/s | 1534.63 MBit/s
> 
>    - 'source-code' (800 MiB) This dataset is a tarball of the source-code
>    from a
>    linux-kernel.
> 
>    algorithm | ratio ??| compression ???| decompression
>    deflate ??| ???3.27 | ??42.48 MBit/s | ?250.36 MBit/s
>    lz4hc ????| ???2.40 | ?104.14 MBit/s | 1150.53 MBit/s
>    lzo ??????| ???2.27 | ?444.77 MBit/s | ?886.97 MBit/s
>    lz4 ??????| ???2.18 | ?453.08 MBit/s | 1101.45 MBit/s
>    842 ??????| ???1.65 | ??64.10 MBit/s | ?158.40 MBit/s
>    zbewalgo ?| ???1.19 | ??52.89 MBit/s | ?197.58 MBit/s
> 
>    - 'hpcg' (8 GiB) This dataset is a (partial) memory-snapshot of the
>    running hpcg-benchmark. At the time of the snapshot, that application
>    performed a sparse matrix - vector multiplication.
> 
>    algorithm | ratio ??| compression ???| decompression
>    zbewalgo ?| ??16.16 | ?179.97 MBit/s | ?468.36 MBit/s
>    deflate ??| ???9.52 | ??65.11 MBit/s | ?632.69 MBit/s
>    lz4hc ????| ???4.96 | ?193.33 MBit/s | 1607.12 MBit/s
>    842 ??????| ???4.20 | ?150.99 MBit/s | ?316.22 MBit/s
>    lzo ??????| ???4.14 | ?922.74 MBit/s | ?865.32 MBit/s
>    lz4 ??????| ???3.79 | ?908.39 MBit/s | 1375.33 MBit/s
> 
>    - 'partdiff' (8 GiB) Array of double values. Adjacent doubles are similar,
>    but
>    not equal. This array is produced by a partial differential equation
>    solver
>    using a Jakobi-implementation.
> 
>    algorithm | ratio ??| compression ???| decompression
>    zbewalgo ?| ???1.30 | ?203.30 MBit/s | ?530.87 MBit/s
>    deflate ??| ???1.02 | ??37.06 MBit/s | 1131.88 MBit/s
>    lzo ??????| ???1.00 | 1741.46 MBit/s | 2012.78 MBit/s
>    lz4 ??????| ???1.00 | 1458.08 MBit/s | 2013.88 MBit/s
>    lz4hc ????| ???1.00 | ?173.19 MBit/s | 2012.37 MBit/s
>    842 ??????| ???1.00 | ??64.10 MBit/s | 2013.64 MBit/s

Hm, mixed feelings.

	-ss