Greg Freemyer wrote:
On 10/30/07, Aaron Kulkis <akulkis00@hotpop.com> wrote:
Robert Lewis wrote:
I recently bought a 64 bit machine and have 10.3 loaded . It seems very fast.
I am trying to appraise if the advantages of having some software not work because of driver issues is worth it.
Has anyone run benchmarks on an identical system with 32 bit vrs 64 bit?
Do we have a list of software that is known not to work on 64-bit? Any defined group tracking this and championing gettin the remainder fixed.
I know this is a generalized question but I am just trying to appraise the gain vrs pain of deciding to stay with 64-bit ? Most data isn't 64-bit. In fact, a large chunk of it is still 16-bit, and even 8 bit (ASCII text, for example).
Most of the speed increase you are seeing is from:
the faster clock speed of your new CPU compared to the last one you had.
wider data buses into and out of the on-chip cache.
floating point operations (where applicable).
You won't see a significant difference between 32-bit and 64-bit system performance until you are running some software which uses lots of 64-bit integers, or is very intensive in floating-point operations.
Surprisingly (to me at least) we are seeing a speed improvement with a specialized version of dd (dcfldd) going against raw disks.
Why is it surprising that dd (which just moves large chunks of data) would be improved by a movement from 4-byte natural word size to 8-byte natural word size? That's like being surprised that thicker pipes can move more gallons of water per hour.
ie. dcfldd if=/dev/sdb of=/dev/sdc bs=4k and dcfldd if=/dev/sdc of=/dev/null bs=4k
Were still putting together a performance matrix, but we're planning to test:
32-bit kernel - 32-bit app 64-bit kernel - 32-bit app 64-bit kernel - 64-bit app
So far we've tested the last 2 and are seeing about a 25% improvement by just recompiling dcfldd as a 64-bit app. I was not expecting that at all.
Greg
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