Re: How to limit amount of virtual memory used for files (was: Re: Tuning ZFS memory usage on NetBSD - call for advice)

[Mike Pumford <mpumford%mudcovered.org.uk@localhost>]

On 22/09/2022 06:44, Lloyd Parkes wrote:

> Can we put together a catalogue of clearly defined problems so that we 
> can reproduce them and investigate further? While Håvard appears to have 
> solved his problem, I'm pretty sure I have an unused G4 Mac Mini of my 
> own that I can try and reproduce his problem on.
So I changed vm.filemin and vm.filemax to solve my excessive swapping 
issues. Basically the system was preferring to keep file cache around 
and was evicting memory for processes that consumed swap (so data pages 
I'm assuming) rather than file cache. Under heavy memory/file usage 
(pkgsrc bulk builds) any large process running at the time of the build 
ended up going non-responsive.

So it could be that the all that needs to change here are the defaults 
for those parameters.

For the record I have:
vm.filemax=10
vm.filemin=1

in /etc/sysctl.conf on a 16GB 9.3-STABLE system. The system can 
comfortably use more memory than that for file cache. As I write this 
message its currently using 9GB for file cache (which I don't see as a 
problem as there are no other demands on the system memory at the 
moment. Starting a new process like firefox correctly dumped file cache 
over other memory with this config. Also long running firefox processes 
remained responsive both during and after the builds with this change.

Mike