linux-kernel - Re: [PATCH v7 0/5] Update LZ4 compressor module

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Date:   Thu, 9 Feb 2017 11:56:17 +0100
From:   Sven Schmidt <4sschmid@...ormatik.uni-hamburg.de>
To:     Minchan Kim <minchan@...nel.org>
Cc:     akpm@...ux-foundation.org, bongkyu.kim@....com,
        rsalvaterra@...il.com, sergey.senozhatsky@...il.com,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        herbert@...dor.apana.org.au, davem@...emloft.net,
        linux-crypto@...r.kernel.org, anton@...msg.org, ccross@...roid.com,
        keescook@...omium.org, tony.luck@...el.com
Subject: Re: [PATCH v7 0/5] Update LZ4 compressor module

Hey Minchan,

On Thu, Feb 09, 2017 at 08:31:21AM +0900, Minchan Kim wrote:
> Hello Sven,
> 
> On Sun, Feb 05, 2017 at 08:09:03PM +0100, Sven Schmidt wrote:
> > 
> > This patchset is for updating the LZ4 compression module to a version based
> > on LZ4 v1.7.3 allowing to use the fast compression algorithm aka LZ4 fast
> > which provides an "acceleration" parameter as a tradeoff between
> > high compression ratio and high compression speed.
> > 
> > We want to use LZ4 fast in order to support compression in lustre
> > and (mostly, based on that) investigate data reduction techniques in behalf of
> > storage systems.
> > 
> > Also, it will be useful for other users of LZ4 compression, as with LZ4 fast
> > it is possible to enable applications to use fast and/or high compression
> > depending on the usecase.
> > For instance, ZRAM is offering a LZ4 backend and could benefit from an updated
> > LZ4 in the kernel.
> > 
> > LZ4 homepage: http://www.lz4.org/
> > LZ4 source repository: https://github.com/lz4/lz4
> > Source version: 1.7.3
> > 
> > Benchmark (taken from [1], Core i5-4300U @1.9GHz):
> > ----------------|--------------|----------------|----------
> > Compressor      | Compression  | Decompression  | Ratio
> > ----------------|--------------|----------------|----------
> > memcpy          |  4200 MB/s   |  4200 MB/s     | 1.000
> > LZ4 fast 50     |  1080 MB/s   |  2650 MB/s     | 1.375
> > LZ4 fast 17     |   680 MB/s   |  2220 MB/s     | 1.607
> > LZ4 fast 5      |   475 MB/s   |  1920 MB/s     | 1.886
> > LZ4 default     |   385 MB/s   |  1850 MB/s     | 2.101
> > 
> > [1] http://fastcompression.blogspot.de/2015/04/sampling-or-faster-lz4.html
> > 
> > [PATCH 1/5] lib: Update LZ4 compressor module
> > [PATCH 2/5] lib/decompress_unlz4: Change module to work with new LZ4 module version
> > [PATCH 3/5] crypto: Change LZ4 modules to work with new LZ4 module version
> > [PATCH 4/5] fs/pstore: fs/squashfs: Change usage of LZ4 to work with new LZ4 version
> > [PATCH 5/5] lib/lz4: Remove back-compat wrappers
> 
> Today, I did zram-lz4 performance test with fio in current mmotm and
> found it makes regression about 20%.
> 
> "lz4-update" means current mmots(git://git.cmpxchg.org/linux-mmots.git) so
> applied your 5 patches. (But now sure current mmots has recent uptodate
> patches)
> "revert" means I reverted your 5 patches in current mmots.
> 
>                      revert    lz4-update
> 
>       seq-write       1547       1339      86.55%
>      rand-write      22775      19381      85.10%
>        seq-read       7035       5589      79.45%
>       rand-read      78556      68479      87.17%
>    mixed-seq(R)       1305       1066      81.69%
>    mixed-seq(W)       1205        984      81.66%
>   mixed-rand(R)      17421      14993      86.06%
>   mixed-rand(W)      17391      14968      86.07%

which parts of the output (as well as units) are these values exactly?
I did not work with fio until now, so I think I might ask before misinterpreting my results.
 
> My fio description file
> 
> [global]
> bs=4k
> ioengine=sync
> size=100m
> numjobs=1
> group_reporting
> buffer_compress_percentage=30
> scramble_buffers=0
> filename=/dev/zram0
> loops=10
> fsync_on_close=1
> 
> [seq-write]
> bs=64k
> rw=write
> stonewall
> 
> [rand-write]
> rw=randwrite
> stonewall
> 
> [seq-read]
> bs=64k
> rw=read
> stonewall
> 
> [rand-read]
> rw=randread
> stonewall
> 
> [mixed-seq]
> bs=64k
> rw=rw
> stonewall
> 
> [mixed-rand]
> rw=randrw
> stonewall
> 

Great, this makes it easy for me to reproduce your test.

Thanks,

Sven