Slow read speeds from {xfs,reiserfs} encrypted cache only

I noticed my cache read speeds were quite slow and did some investigation. I had recently switched from btrfs-encrypted cache to xfs-encrypted cache due. It seems that on my system my read speeds with xfs/reiserfs encrypted cache are extremely slow, while unencrypted or btrfs-encrypted is much faster. Any ideas what could be going on? Anyone else have this issue?

 

reiserfs-encrypted

• 130 MB/s write
• 25 MB/s read

   

xfs-encrypted 

• 130 MB/s write
• 20 MB/s read

 

xfs-unencrypted

• 200 MB/s write
• 450 MB/s read

 

btrfs-encrypted

• 130 MB/s write
• 450 MB/s read

Methodology:
      
# urandom to ensure it's not due to the SSD controller compressing the data

dd if=/dev/urandom of=/mnt/cache/test bs=4M count=256 conv=fsync

# remove from cache before reading

sync; echo 3 > /proc/sys/vm/drop_caches
dd of=/dev/null if=/mnt/cache/test bs=4M count=256 

 

Also verified speeds with dstat -D sdb. Writing/reading to array itself is as expected, ~80 MB/s for both read and write.

 

SSD Cache drive: ATA SAMSUNG SSD 830 (scsi)
CPU: Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz

Unraid: 6.8.3

 

changes to blockdev readahead, io scheduler, nr_requests all have no effect and are set to default and rebooted. All dockers/vm/scripts off. All shares set to not use cache.