Re: XCode 2.4 and 32/64-bit universal binaries
Re: XCode 2.4 and 32/64-bit universal binaries
- Subject: Re: XCode 2.4 and 32/64-bit universal binaries
- From: Ian Kemmish <email@hidden>
- Date: Sun, 20 Aug 2006 21:35:05 +0100
On 20 Aug 2006, at 8:02 pm, Herbie Robinson <hrob@curbside-
recording.com> wrote:
At 4:52 PM +0300 8/17/06, Artemiy Pavlov wrote:
Okay, so, what about a 32-bit app on a 64 bit CPU vs. the same app
compiled for that target 64-bit CPU? Will the latter work faster or
no?
The experience with RISC machines (that I am aware of) is that 64 bit
applications often run a little slower because the cache footprint
becomes larger and there are more cache misses.
Absolutely correct. I can report two different measurements, both
obtained using my Jaws PostScript interpreter on a broad mix of
benchmark data. On the DEC Alpha, code with 64 bit integers and 32
bit pointers ran about 7% faster than code with 64 bit pointers. By
the time Silicon Graphics had got around to providing a 64 bit OS,
this difference was closer to 3%.
I attributed this shrinking difference to the fact that caches have
got larger over time. Intel CPUs often seem to have bigger caches
than other brands, so for a single task, the difference in
performance may by now be imperceptible. However, if an Audio Unit
is part of a process with a large working set (as seems entirely
possible), the difference may reappear.
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Ian Kemmish 18 Durham Close, Biggleswade, Beds
SG18 8HZ
email@hidden Tel: +44 1767 601361 Mob: +44 7952
854387
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