🚀 go-pugleaf

Brian Willoughby writes
| Bernhard Nocker writes
| | My NeXTdimension Turbo and another NeXTdimension Turbo are suffering from  
| | a strange behaviour which causes system panic more than twice a day!!
| | The /usr/adm/messages and console simply reports "mach panic ... No more  
| | room in kernel map" and the system dies. Sometimes without syncing which  
| | causes some other problems!
| 
| I have a 25 MHz NeXTdimension and I have had at least four of these exact  
| panic messages. [...]
| 
| My machine has NOT been heavily loaded at these times!
| 
| Its about time to bug_next@next.com

Well, I did call 800/848-NeXT:

Apparently, this panic is related to the kernel nbuf parameter.  I had been  
booting with nbuf set to 359 on my 28MB NeXTcube.  A local Unix-head suggested  
that NeXT's cache limit of 10% of the installed RAM was far too small - and  
therefore recommended the maximum setting possible.  For 28MB RAM, 2.79MB was  
the highest amount I could allocate using nbuf=359

All was well until I installed 3.0 and starting experiencing at least one  
system panic per day.  Each time, the line in /usr/adm/messages read something  
like this:
Sep 29 09:39:05 sounds mach: panic: (Cpu 0) No more room in kernel map

A call to NeXT Systems Support was returned the next business day with the  
suggestion that I either get more RAM, or reduce nbuf below 256.  The engineer  
stated that the 3.0 kernel was now larger and that there were known problems  
with high nbuf values, but that 255 had been verified as safe to use.

If you have less than 19.9MB of System RAM, the kernel will limit the cache to  
10% of your RAM regardless of your setting and you'll probably be safe (IMHO).

I've been running for 48 hours without a single pesky panic, so I figured it  
was close enough to proven to share with the community before someone else  
starts getting a headache too.
-- 
Brian Willoughby	Software Design Engineer, BSEE NCSU
BrianW@SoundS.WA.com	Sound Signal Processing Software and Consulting
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