ZRAM Will See Greater Performance On Linux 5.1 - It Changed Its Default Compressor

[Mario Junior]

So, LZ4 or zstd?

[ipsirc]

So, LZ4 or zstd?

lz4 on single core, pzstd on multicore

[oibaf]

Out of curiosity I did a test comparing rlo-rle vs. lz4 vs. zstd when setting a ext4 partition on a zram device on Ubuntu 20.04. Here is how I created it:

ZRAM_SIZE=2048M
if [ ! -e /tmp/zram ]; then
  modprobe zram num_devices=1 && \
   echo `nproc` > /sys/block/zram0/max_comp_streams && \
   echo zstd > /sys/block/zram0/comp_algorithm && \
   echo Size: $ZRAM_SIZE
   echo "$ZRAM_SIZE" > /sys/block/zram0/disksize && \
   mkfs.ext4 /dev/zram0 && \
   mkdir -p /tmp/zram && \
   mount /dev/zram0 /tmp/zram && \
   chmod 777 /tmp/zram && \
   chmod +t /tmp/zram
fi

I rebooted at every algo change and repeated a test procedure I am using on that partition 3 times. I did those tests within a 2vCPU VM on a host with other VMs running, so it's not very reliable, but that's my use case. The tests are not very conclusive:

• with lzo-rle (default): 149s - 141s - 144s
• with lz4: 160s - 147s - 132s
• with zstd: 148s - 133s - 139s

[Mario Junior]

Out of curiosity I did a test comparing rlo-rle vs. lz4 vs. zstd when setting a ext4 partition on a zram device on Ubuntu 20.04. Here is how I created it:

ZRAM_SIZE=2048M
if [ ! -e /tmp/zram ]; then
modprobe zram num_devices=1 && \
echo `nproc` > /sys/block/zram0/max_comp_streams && \
echo zstd > /sys/block/zram0/comp_algorithm && \
echo Size: $ZRAM_SIZE
echo "$ZRAM_SIZE" > /sys/block/zram0/disksize && \
mkfs.ext4 /dev/zram0 && \
mkdir -p /tmp/zram && \
mount /dev/zram0 /tmp/zram && \
chmod 777 /tmp/zram && \
chmod +t /tmp/zram
fi

I rebooted at every algo change and repeated a test procedure I am using on that partition 3 times. I did those tests within a 2vCPU VM on a host with other VMs running, so it's not very reliable, but that's my use case. The tests are not very conclusive:

• with lzo-rle (default): 149s - 141s - 144s
• with lz4: 160s - 147s - 132s
• with zstd: 148s - 133s - 139s

I couldn't understand this test. What did you want to show?

[oibaf]

I couldn't understand this test. What did you want to show?

I reported the times of a read/write test of a custom procedure I am using, using a zram partition compressed with 3 different methods.