SUMMARY/UPDATE: 4 cpus / SunOS 4.1.3_u1

From: Michael Blandford (mikey@azalea.LANL.GOV)
Date: Tue Feb 13 1996 - 11:17:25 CST

Here was the original question:

: I have a sparc 10 running 4.1.3_u1 with 2 single 50 cpus. This works
: fine and has been running for almost 2 years. I now have 2 dual 50
: cpus. The numbers on them are:

: 501260900957
: 02 Rev 50

: If I install these, then I get a data exception error immeadiately
: while loading the kernel. Sun says these are only supported un SLOWaris
: but other people I have talked to say they will work under 4.1.X with
: patches but no one seems to know which patches.

: Any ideas?

Ok. Heres the update. Many people said that running 4 cpus could be
slower than 2. I guess I dont really need 4 since I am running 2 singles now.
However, I cant even boot with a single dual cpu. If I could that would
be more than fine with me.

Here is a quick history. We upgraded many machines from 2 single cpus
to 2 dual cpus. This is the only one running SunOS. The rest run Solaris
with all 4 cpus without problem. Sun is wanting their old cpus back
and we cant return them until we get the new ones to work.

We would be happy running a single dual instead of all 4.

Here are the replies:
I don't have the info handy.... (it's at my last place of employment) ...
but I know with ROSS patches you can run 4 cpus under 4.1.3+

Scott (Thomas Tonino):
Don't please don't qoute me on this:

I THINK [that I read somewhere]{that someone heard that} SunOS 4.1.x only
does Asymmetrical MP. In this case meaning 1 cpu for kernel tasks and 1 for
user tasks.

Wouldn't this men more than 2 CPUs is pointless?

Casper Dik <casper@holland.Sun.COM>:
If they don't have an external 1MB cache they won't work under SunOS 4.1.x.
If they have a 1MB external cache each they might work udner SunOS 4.1.x
but it's not supported.

(BTW, Solaris 2.x is faster than SunOS 4.1.x in most things esp. if you
use two or emore processors)

David Fetrow <>:
 You are aware that 4 CPU's in a SunOS 4 machine tends to run slower
for most applications than two due to overhead conflicts, right?

David Hawes <>:try using 4.1.4 it has the 4.1.3 kernel jumbo patch included.
also you should reconsider using solaris 2.5 it doesn't seam as bad as earlier
versions and ther kernel is multi-threaded which makes it better for
multiprocessor machines. 4.1.x will not run much faster with 4 processors than
it does with 2 as only one processor can be in the kernel (ie interrupts or
system calls) at the same time and the others just have to sit in spin locks
while they wait for it to finish. Although with 2 processors 4.1.4 may be
faster than solaris 2.5 for some set ups its almost certainly going to be
slower with 4 processors.



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