[gclist] 64 bit machines and conservatism

David Gadbois gadbois@cyc.com
Mon, 15 Dec 1997 16:25:33 -0600

   From: boehm@hoh.mti.sgi.com (Hans Boehm)
   Date: Mon, 15 Dec 1997 13:28:05 -0800

   I still suspect that anything near a 4GB garbage collected heap is
   rare.  But that may not be the only thing you want to address.

My customers have operational systems running with heaps in the 2-6 GB
range.  It works because the data are mostly static over long (weeks)
periods, but you do have to be very, very careful about scheduling
GC's that may grovel over a large portion of the heap.

I did look into swizzling techniques to keep pointer sizes down to 32
bits, but the engineering cost tradeoff was not worthwhile in the face
of relatively cheap big-memory machines.  The tradeoff may be
different for broader-market type stuff, and who knows what wacky
things might happen in the consumer market.

--David Gadbois