From: Peter Galbavy <peter@wonderland.org>
   Date: Thu, 18 Apr 1996 18:10:44 +0100 (BST)

   > BTW, SparcLinux now does SMP on the Sparc20.  3 minutes kernel
   > recompiles on dual CPU Ross HyperSparc 120Mhz chips.  Good job David.

   This sounds good, but is it *real* SMP with data structure level locking
   or AMP like 4.1.2 and above do ? I know too little about the Linux SMP
   architechtures to even guess.

It's still a SunOS style giant kernel lock implementation, we wanted
to get something working quickly as a proof of concept.

Next we will be sprinkling spin locks around major subsections of the
kernel to allow real parallel kernel activity then perhaps an even
finer grained implementation after that.  (never a true
per-every-data-structure locking style like Solaris, SGI got SMP right
and they do medium grained locking, solaris spends 50% of it's time
playing with locks for only a slight gain in very specialized cases).

Actually we have a scheme that will make Linux scalable to n-CPU's
where n can't fit in an unsigned char. ;-)

Later,
David S. Miller
davem@caip.rutgers.edu