RE2 Performance

[Jeff Weinstein]

	Getting an RE2 is the best thing you can do to help your
	X performance on a Personal Iris.  The RE2 has several
	advantages over the RE1:

		1) Does logicop in hardware.  That means that
		   when you specify XOR we don't have to read
		   the bits back, twiddle them on the host,
		   then write them back to the graphics board.

		2) Writing 8 bit deep images is much faster since
		   the RE2 can unpack 4 pixels from a single
		   32bit words, whereas the RE1 had to have
		   one pixel per word, no matter what.

		3) The RE2 is faster than the RE1.

	You may not see a huge speedup with the RE2 with today's
	X server, but in the future we will be taking advantage
	of the RE2 in a much bigger way.

	If you are serious about running X you probably want
	an RE2.

	To find out which RE chip you have run the 'hinv' program.
	If if says 'Graphics Board: GR1.1' then you have an RE1,
	GR1.2 is an RE2.

Jeff Weinstein - X Protocol Police
Silicon Graphics, Inc., Entry Systems Division, Window Systems
jsw at xhead.esd.sgi.com
Any opinions expressed above are mine, not sgi's.