Re: Swap filling up, usermode process swap usage doesn't explain

From: Pete Wright <pete_at_nomadlogic.org>
Date: Wed, 19 Jul 2023 18:34:14 UTC 

On 7/19/23 07:49, Scott Gasch wrote:
> I am running a 13.2-RELEASE GENERIC kernel and seeing a pattern where, 
> after about 10 days of uptime, my swap begins to fill up.
> 
<snip>
> 
> At least they agree about it being 11G.  Is this kernel memory being 
> paged out to swap?  The machine has 128G of physical memory and isn't 
> under very heavy load at the moment.
> 

Are you running ZFS by any chance?  If so its possible it is trying to 
use as much memory as possible for the ARC.  I've seen this on a few 
systems which lots of memory.  One way to tell is to run "top" and look 
at the ARC stats:

last pid: 71322;  load averages:  1.02,  0.94,  0.87              up 
8+18:38:34  11:31:26
376 processes: 1 running, 146 sleeping, 229 zombie
CPU:  0.6% user,  0.0% nice,  6.5% system,  0.0% interrupt, 93.0% idle
Mem: 3599M Active, 18G Inact, 4132M Laundry, 4272M Wired, 892M Free
ARC: 1749M Total, 651M MFU, 239M MRU, 1864K Anon, 13M Header, 844M Other
      216M Compressed, 758M Uncompressed, 3.52:1 Ratio



On a few of my larger memory systems I cap the ARC by setting this 
sysctl knob (this is like 45G on my system):
vfs.zfs.arc.max=45000000000


-pete


-- 
Pete Wright
pete@nomadlogic.org
@nomadlogicLA