ZFS encrypted cache performance

[pappaq]

Hello there,

 

in the process of converting my cache pool to zfs encrypted I noticed spikes in CPU usage, while the mover is moving the appdate etc. back onto the cache. I've then tried to copy a file from an SSD to the cache. When writing to the cache the CPU spikes and the copy process pauses for a few seconds, kworker tasks ramp up and the copy process continues. I've got no issue with zfs using CPU but with sluggish writes.

 

On the other hand copying FROM the cache pool to the said SSD does not trigger this behavior and everything runs smooth.

 

My concern is that this haltering behavior has an impact on the future use by dockers and VMs etc.

 

Is there anything I can do about it or is it an expected behavior? I've intentionally downgraded to 6.12.3 because of known issues regarding AVX2.

dringenet-ms-diagnostics-20231022-1026.zip

Edited October 22, 2023 by pappaq

[JorgeB]

2 hours ago, pappaq said:

I've intentionally downgraded to 6.12.3 because of known issues regarding AVX2.

That should only affect zfs native encryption, but any encryption always adds some overhead, though should not be really noticeable with a modern CPU, you can try without it to see if it's noticeably faster.

[pappaq]

I've got no problem with the encryption overhead but the stuttering in transfers. That seems odd...

[pappaq]

The stutter only occures when copying to the cachepool and only when bigger files are copied. I'm fine with this because the overall performance of the system has increased dramatically.

[hoejholm]

I was on 6.12.3 when I experienced the same after rebuilding my server, i downgraded to 6.12.2 and that fixed it.

I did this based on other forum posts speaking about the AVX issue.