Memory usage appears a bit high

James B. Byrne byrnejb at
Wed Jan 16 17:31:33 UTC 2019

We have an Cyrus IMAP service running on a BHyve FreeBSD-11.2p7 vm. 
It has 4 Gb allocated.  I have noticed that top reports this:

Mem: 164M Active, 204M Inact, 22M Laundry, 3426M Wired, 111M Free

which indicates that more than 75% of the allocated memory is
permanently wired to the kernel and unavailable for anything else.  I
ran netstat -m to see the assignment and got this result:

# netstat -m
1027/1508/2535 mbufs in use (current/cache/total)
1024/762/1786/251314 mbuf clusters in use (current/cache/total/max)
1024/747 mbuf+clusters out of packet secondary zone in use
0/14/14/125657 4k (page size) jumbo clusters in use
0/0/0/37231 9k jumbo clusters in use (current/cache/total/max)
0/0/0/20942 16k jumbo clusters in use (current/cache/total/max)
2304K/1957K/4261K bytes allocated to network (current/cache/total)
0/0/0 requests for mbufs denied (mbufs/clusters/mbuf+clusters)
0/0/0 requests for mbufs delayed (mbufs/clusters/mbuf+clusters)
0/0/0 requests for jumbo clusters delayed (4k/9k/16k)
0/0/0 requests for jumbo clusters denied (4k/9k/16k)
0 sendfile syscalls
0 sendfile syscalls completed without I/O request
0 requests for I/O initiated by sendfile
0 pages read by sendfile as part of a request
0 pages were valid at time of a sendfile request
0 pages were requested for read ahead by applications
0 pages were read ahead by sendfile
0 times sendfile encountered an already busy page
0 requests for sfbufs denied
0 requests for sfbufs delayed

There does not seem to be any evidence of memory pressure here.

Is the kernel glomping of most available memory expected behaviour? 
In other words, if I increase the memory allocated to the vm will the
kernel simply eat the increase as well? Do I have a problem somewhere?
 This is not a very busy server and 4 GB seemed a generous allowance
when we set it up.

***          e-Mail is NOT a SECURE channel          ***
        Do NOT transmit sensitive data via e-Mail
 Do NOT open attachments nor follow links sent by e-Mail

James B. Byrne                mailto:ByrneJB at
Harte & Lyne Limited
9 Brockley Drive              vox: +1 905 561 1241
Hamilton, Ontario             fax: +1 905 561 0757
Canada  L8E 3C3

More information about the freebsd-questions mailing list