Odd slow-down issue

[Michael Graff <michael_graff%isc.org@localhost>]

I have seen this four times now.  Once on a "server" (intel dual-core, no X11 
running but it does have a built-in VGA, mostly unused) and three times on my 
laptop.

Symptoms are things like "sleep 1" taking a variable number of 
seconds.  "systat vmstat 1" will update once every 5-10 seconds or so.  On 
the laptop, all disk I/O seems to stop, the cursor does not move but jumps, 
and while the windows are responsive, the "focus under cursor" does not cause 
the actual window highlight to change as it should.

Typing takes 3-5 seconds to appear, and then does so in batches.  Mistyping a 
command means that window is dead.  Starting any application like "systat" 
takes up to 30 seconds.

These systems have completely different SMP (laptop is 1-core, server is 
2-core), graphics, network cards, etc.  The only commonality is that each is 
running NetBSD, and SEEMS to be triggered by high CPU or disk load.  I cannot 
recreate it on demand.

laptop:
NetBSD lapdog.flame.org 4.99.55 NetBSD 4.99.55 (GENERIC) #1: Tue Mar  4 
15:57:40 UTC 2008  
explorer%speedy.home.flame.org@localhost:/usr/src/sys/arch/i386/compile/GENERIC 
i386

server:
NetBSD kechara.flame.org 4.99.38 NetBSD 4.99.38 (GENERIC.MP) #0: Wed Nov 28 
00:57:29 UTC 2007  
root@:/u1/os-build/i386/obj/sys/arch/i386/compile/GENERIC.MP i386

So, this has been around for a while...

--Michael