On (22/11/07 11:08), Minchan Kim wrote:
[..]
> I am thinking like this:
>
> * Without recomp_algo setup, user can do whatever they want on the fly
>
>
> echo "type=idle threshold=3000 algo=zstd" > recompress
>
> Later they could do
>
> echo "type=idle threshold=3000 algo=deflate" > recompress
By "without recomp_algo setup" you mean that user doesn't configure
anything before `echo XG > zramX/disksize`? Currently algorithm and
recomp algorithm need to be selected at the same time - before zram
device is initialised, because we use the same code and same approaches:
we need to have zcomp back-ends in per-CPU data in zram read/write/recompress.
Creating per-CPU zcomps on the fly is probably going to be a little bit
intrusive to zram.
What I currently have is as follows.
A copy paste from my test script:
- init device
echo "algo=lz4 priority=1" > /sys/block/zram0/recomp_algorithm
echo "algo=zstd priority=2" > /sys/block/zram0/recomp_algorithm
echo "algo=deflate priority=3" > /sys/block/zram0/recomp_algorithm
echo 5G > /sys/block/zram0/disksize
Various recompression use cases:
- recompress huge pages using all secondary algos in order of priority
echo "type=huge" > /sys/block/zram0/recompress
- recompress huge pages using zstd only
echo "type=huge algo=zstd" > /sys/block/zram0/recompress
- recompress all pages using lz4
echo "algo=lz4" > /sys/block/zram0/recompress
- recompress idle pages, use all algos in priority order, with threshold
echo "type=idle threshold=3000" > /sys/block/zram0/recompress
- recompress idle pages, using zstd only, with threshold
echo "algo=zstd type=idle threshold=2000" > /sys/block/zram0/recompress
