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

[Minchan Kim]

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%

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