System hangs when zswap gets filled up

[materemias]

I have some ram heavy workloads on a machine having 128GB of ram. I use a combination of swapspace and zram to cover the extending memory need of my processes on demand.
When zram gets filled up I got Under memory pressure, flushing caches error and system hangs for 30-60 seconds. I have pretty standard config:

zram-size = ram / 2
compression-algorithm = zstd

If i turn zram device off i still got stutters, but not that long. Do you have an advice what I could try to ease the situation?

[AlleyPally]

Hello @materemias ! While I am not qualified and simply throwing guesses around, zswap is not compatible with zram. You have to use one or the other!

Quote from the Arch wiki:

If the related zswap kernel feature remains enabled, it will prevent zram from being used effectively. This is because zswap functions as a swap cache in front of zram, intercepting and compressing evicted memory pages before they can reach zram. Despite the output of zramctl(8), most of zswap is unused in this circumstance. Therefore, it's recommended to permanently disable zswap using the kernel parameter or sysfs setting before starting.

In order to disable the aforementioned zswap feature, check this out!

If you have zswap disabled already and are using your swap device for writeback, I am not sure how your issue can be remedied. Apologies!

Have a good day!