Re: zram: per-cpu compression streams

[Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>]

Hello,

On (03/31/16 07:12), Minchan Kim wrote:
[..]
> > I used a bit different script. no `buffer_compress_percentage' option,
> > because it provide "a mix of random data and zeroes"
> 
> Normally, zram's compression ratio is 3 or 2 so I used it.
> Hmm, isn't it more real practice usecase?

this option guarantees that the supplied to zram data will have
a requested compression ratio? hm, but we never do that in real
life, zram sees random data.

> If we don't use buffer_compress_percentage, what's the content in the buffer?

that's a good question. I quickly looked into the fio source code,
we need to use "buffer_pattern=str" option, I think. so the buffers
will be filled with the same data.

I don't mind to have buffer_compress_percentage as a separate test (set
as a local test option), but I think that using common buffer pattern
adds more confidence when we compare test results.

[..]
> > hm, but I guess it's not enough; fio probably will have different
> > data (well, only if we didn't ask it to zero-fill the buffers) for
> > different tests, causing different zram->zsmalloc behaviour. need
> > to check it.
[..]
> > #jobs4               	           	           
> > READ:      8720.4MB/s	 7301.7MB/s	 7896.2MB/s
> > READ:      7510.3MB/s	 6690.1MB/s	 6456.2MB/s
> > WRITE:     2211.6MB/s	 1930.8MB/s	 2713.9MB/s
> > WRITE:     2002.2MB/s	 1629.8MB/s	 2227.7MB/s
> 
> Your case is 40% win. It's huge, Nice!
> I tested with your guide line(i.e., no buffer_compress_percentage,
> scramble_buffers=0) but still 10% enhance in my machine.
> Hmm,,,
> 
> How about if you test my fio job.file in your machine?
> Still, it's 40% win?

I'll retest with new config.

> Also, I want to test again in your exactly same configuration.
> Could you tell me zram environment(ie, disksize, compression
> algorithm) and share me your job.file of fio?

sure.

3G, lzo


--- my fio-template is

[global]
bs=4k
ioengine=sync
direct=1
size=__SIZE__
numjobs=__JOBS__
group_reporting
filename=/dev/zram0
loops=1
buffer_pattern=0xbadc0ffee
scramble_buffers=0

[seq-read]
rw=read
stonewall

[rand-read]
rw=randread
stonewall

[seq-write]
rw=write
stonewall

[rand-write]
rw=randwrite
stonewall

[mixed-seq]
rw=rw
stonewall

[mixed-rand]
rw=randrw
stonewall


#separate test with
#buffer_compress_percentage=50



--- my create-zram script is as follows.


#!/bin/sh

rmmod zram
modprobe zram

if [ -e /sys/block/zram0/initstate ]; then
        initdone=`cat /sys/block/zram0/initstate`
        if [ $initdone = 1 ]; then
                echo "init done"
                exit 1
        fi
fi

echo 8 > /sys/block/zram0/max_comp_streams

echo lzo > /sys/block/zram0/comp_algorithm
cat /sys/block/zram0/comp_algorithm

cat /sys/block/zram0/max_comp_streams
echo $1 > /sys/block/zram0/disksize





--- and I use it as


#!/bin/sh

DEVICE_SZ=$((3 * 1024 * 1024 * 1024))
FREE_SPACE=$(($DEVICE_SZ / 10))
LOG=/tmp/fio-zram-test
LOG_SUFFIX=$1

function reset_zram
{
        rmmod zram
}

function create_zram
{
        ./create-zram $DEVICE_SZ
}

function main
{
        local j
        local i

        if [ "z$LOG_SUFFIX" = "z" ]; then
                LOG_SUFFIX="UNSET"
        fi

        LOG=$LOG-$LOG_SUFFIX

        for i in {1..10}; do
                reset_zram
                create_zram

                cat fio-test-template | sed s/__JOBS__/$i/ | sed s/__SIZE__/$((($DEVICE_SZ/$i - $FREE_SPACE)/(1024*1024)))M/ > fio-test
                echo "#jobs$i" >> $LOG
                time fio ./fio-test >> $LOG
        done

        reset_zram
}

main




-- then I use this simple script

#!/bin/sh

if [ "z$2" = "z" ]; then
        cat $1 | egrep "#jobs|READ|WRITE" | awk '{printf "%-15s %15s\n", $1, $3}' | sed s/aggrb=// | sed s/,//
else
        cat $1 | egrep "#jobs|READ|WRITE" | awk '{printf " %-15s\n", $3}' | sed s/aggrb=// | sed s/\#jobs[0-9]*// | sed s/,//
fi




as 

	./squeeze.sh fio-zram-test-4-stream > 4s
	./squeeze.sh fio-zram-test-8-stream A > 8s
	./squeeze.sh fio-zram-test-per-cpu A > pc

and

	paste 4s 8s pc > result


	-ss