bin/58001: systat -w1 vmstat reports "Cannot get buffers;Cannot allocate memory"

[michael.cheponis%gmail.com@localhost]

>Number:         58001
>Category:       bin
>Synopsis:       systat -w1 vmstat reports "Cannot get buffers;Cannot allocate memory"
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 06 07:40:01 +0000 2024
>Originator:     Mike Cheponis
>Release:        10.0_RC5
>Organization:
self
>Environment:
NetBSD SS.Culver.Net 10.0_RC5 NetBSD 10.0_RC5 (GENERIC) #0: Tue Feb 27 05:27:39 UTC 2024  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC am
>Description:
systat -w1 vmstat reports "Cannot get buffers;Cannot allocate memory"

at the same time, in a different window, this command is running on a 2TB disk:

dd if=/dev/sd0a of=/dev/null bs=1m

avail memory = 31424 MB

If this is not running, the error does not appear

>swapctl -l
Device       1048576-blocks     Used    Avail Capacity  Priority
/dev/dk2              32507        0    32507     0%    0
/r/swapfile0           4096        0     4096     0%    0
Total                 36603        0    36603     0%
 
>How-To-Repeat:
see above
>Fix:
This only occurs when the line: dd if=/dev/sd0a of=/dev/null bs=1m

is running.  I've not tried other possible long-time-running background tasks to see why systat -w1 vmstat is complaining