I've been trying to track this stuff - in fact, I'll likely be
switching from AMD32 to AMD64 in the next few weeks.
I believe I have a handle on the + vs - of 64-bit. It makes sense that
full 64-bit would be slower. At an extreme it halfs the amount of
available memory or doubles the required memory bandwidth, depending
on the work load.
Has anybody taken a look at PostgreSQL to ensure that it uses 32-bit
integers instead of 64-bit integers where only 32-bit is necessary?
32-bit offsets instead of 64-bit pointers? This sort of thing?
I haven't. I'm meaning to take a look. Within registers, 64-bit should
be equal speed to 32-bit. Outside the registers, it would make sense
to only deal with the lower 32-bits where 32-bits is all that is
required.
Cheers,
mark
--
mark@mielke.cc / markm@ncf.ca / markm@nortel.com __________________________
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