Hi,
I have a mystery and am wondering if anyone has ideas.
Ubuntu 16.04.5 Kernel 4.15.0-39
We have incoming UDP data coming in at 2.42Gb/s. The data is written to a 1TB SSD and also processed and some of the output is written to a 2nd 1TB SSD. Every minute data from the 2nd SSD is packaged (including compression) and copied to a hardware encrypted HDD RAID. If the data is "interesting" several minutes of data from the first SSD are copied to the HDD RAID.
All is good if the 2 1TB SSD's are not encrypted. If I use LUKS to encrypt the SSD's, it runs for about 40 minutes and then the "pipe" gets full and we lose packets. ethtool reports rx_missed_errors.
I am trying to understand why simply turning on encryption would cause the problem and if anyone has ideas.
I have installed the aes kernel modules cryptd, aes_x86_64 and aesni_intel.
The processor is an Intel i9-7920X (12 core, 24 threads). The system load is only 8. Using the program 'glances' I don't see where the disk i/o is getting fully loaded except for 2 seconds out of 60.
I don't expect a magic solution but am hoping for ideas since I've narrowed this down to LUKS vs no LUKS and have installed the AES modules.
I did, however, find this article and wonder if it means something. Just by itself, I wonder if anyone would like to simply comment on the article for academic reasons.
Does it make sense to anyone here for me to attempt to increase the block size? I think it's the -b option to cryptsetup, but that isn't clear to me. A value of 8 would give me 4K, right? (I would just try it but I currently don't have access to the box but likely will tomorrow even if I don't get an answer from anyone.)
Thanks to anyone who reads this and I'm interested in ideas or knowledge or where I can find more information. (I have read the FAQ and I have used the API as well.)
Regards,
Hugh McCurdy
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