🚀 go-pugleaf

In article <1992Nov20.220615.7494@raid.dell.com>
	samf@yosemite.dell.com (Sam Fuller) writes:

>After reviewing the Alpha performance claims, I had the feeling that the
>integer unit did not really run at 133Mhz.  It looked to me that the
>floating point pipeline was superpipelined at 133Mhz, but that the integer
>side ran at a more reasonable 66Mhz.  The pipes can operate independently
>and I imagine be dispatched in parallel, hence the superscalar appelation.

The integer pipeline runs at full speed, but:

	. dual issue is rare in the current implementation with current
	compilers, for integer-only code

	. many instructions, including load and shift, have multi-cycle
	latencies

	. the primary caches are small and the secondary cache has a
	long access time

gcc in particular runs slowly on an Alpha, because it uses a lot of bit
manipulation instructions, makes many memory references, and has a poor
memory access pattern.

--
    John Carr (jfc@athena.mit.edu)