Re: 64-bit vs 32-bit performance ... backwards?

Mark,

On 6/12/06 7:16 PM, "mark(at)mark(dot)mielke(dot)cc" <mark(at)mark(dot)mielke(dot)cc> wrote:

> 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.

The short answer to all of this as shown in many lab tests by us and
elsewhere (see prior post):

- 64-bit pgsql on Opteron is generally faster than 32-bit, often by a large
amount (20%-30%) on queries that perform sorting, aggregation, etc. It's
generally not slower.

- 64-bit pgsql on Xeon is generally slower than 32-bit by about 5%

So if you have Opterons and you want the best performance, run in 64-bit.
If you have Xeons, you would only run in 64-bit if you use more than 4GB of
memory.

- Luke