11.2-STABLE kernel wired memory leak

[Paul Mather]

On Mar 29, 2019, at 5:52 AM, Robert Schulze <rs at bytecamp.net> wrote:

> Hi,
> 
> I just want to report a similar issue here with 11.2-RELEASE-p8.
> 
> The affected machine has 64 GB ram and does daily backups from several
> machines in the night, at daytime there a parallel runs of clamav on a
> specific dataset.
> 
> One symtom is basic I/O-performance: After upgrading from 11.1 to 11.2
> backup times have increased, and are even still increasing. After one
> week of operation, backup times have doubled - without having changed
> anything else.
> 
> Then there is this wired memory and way too lazy reclaim of memory for
> user processes: The clamav scans start at 10:30 and get swapped out
> immediatly. Although vfs.zfs.arc_max=48G, wired is at 62 GB before the
> scans and it takes about 10 minutes for the scan processes to actually
> run on system ram, not swap.
> 
> There is obviously something broken, as there are several threads with
> similar observations.


I am using FreeBSD 12 (both -RELEASE and -STABLE) and your comment about "way too lazy reclaim of memory" struck a chord with me.  On one system I regularly have hundreds of MB identified as being in the "Laundry" queue but FreeBSD hardly ever seems to do the laundry.  I see the same total for days.

When does FreeBSD decide to do its laundry?  Right now "top" is showing 835M in "Laundry" and the system is >99% idle.

How can I get the system to be more proactive about doing its housekeeping when it has idle time?

It would be much nicer to have it do laundry during a calm time rather than get all flustered when it's down to its last pair of socks (metaphorically speaking) and page even more stuff out to swap. :-)

Cheers,

Paul.