kern.ipc.maxpipekva console messages starting with 21.02 upgrade

bldnightowl

I am seeing the following message every 5 seconds on the console (and in the system general log) since upgrading to 21.02 on an SG-3100.

kern.ipc.maxpipekva exceeded; see tuning(7)

That relevant portion of that man page states:

The kern.ipc.maxpipekva loader tunable is used to set a hard limit on the amount of kernel address space allocated to mapping of pipe buffers. Use of the mapping allows the kernel to eliminate a copy of the data from writer address space into the kernel, directly copying the content of mapped buffer to the reader. Increasing this value to a higher setting, such as `25165824' might improve performance on systems where space for mapping pipe buffers is quickly exhausted. This exhaustion is not fatal; however, and it will only cause pipes to fall back to using double-copy.

Any thoughts on why 21.02 is unhappy about my environment / setup when 2.4.5 was not?
What is the best way to configure another value for this kernel parameter?
How do I determine what that better value should be?

jimp

We are tracking some other problems on the 3100 which may be related, but I don't know that anyone else has reported that specific message yet.

What packages do you have enabled on there? And what features? (e.g. IPsec)

bldnightowl

@jimp

Avahi 2.1_1
aws-wizard 0.9
Cron 0.3.7_5
ipsec-profile-wizard 1.0_2
openvpn-client-export 1.5_5

I was running pfBlockerNG like many others, but I have completely removed it for the moment.

I am not using IPSec, but i do have an OpenVPN server running.

I have a moderate number of VLANs.

jimp

I could maybe see Avahi being related but it's hard to say.

Do you have RAM disks enabled for /var and /tmp? I know that consumes kernel memory which could maybe contribute to the error you're seeing.

bldnightowl

@jimp I only had what was configured OOTB for 21.02. However, I have now downgraded to 2.4.5p1 -- so will have to leave this topic for another day.