Itanium float vs int performance

I heard a rumor that floating point operation the the 64bit Itanium
processors perform faster than integer operations. I do not see how
this is possible. Can someone enlighted me? I would appreciate it. If
this is not true, I want to put these rumors to rest among my colleages.

Thanks in advance!

Isaac Gerg wrote:
I heard a rumor that floating point operation the the 64bit Itanium
processors perform faster than integer operations. I do not see how
this is possible. Can someone enlighted me? I would appreciate it. If
this is not true, I want to put these rumors to rest among my colleages.

Thanks in advance!

About Itanium 2: "The resources consist of six integer units, six
multimedia units, two load and two store units, three branch units, two
extended-precision floating-point units, and two additional
single-precision floating-point units."

I don't know what you mean by "faster" at floating point than integer.
They run on the same clock through the same pipeline. There are more
integer units. Itanium 2 scores higher in SPECfp than SPECint, because
these benchmarks are representations of how many times faster your
computer is compared to a Sun Ultra 5 with a 300MHz processor, and that
machine was especially poor at floating point compared to integer. So a
balanced system would get higher SPECfp numbers than SPECint numbers.

Alex
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Alex Johnson wrote:

Isaac Gerg wrote:

I heard a rumor that floating point operation the the 64bit
Itanium processors perform faster than integer operations. I
do not see how this is possible. Can someone enlighted me? I
would appreciate it. If this is not true, I want to put these
rumors to rest among my colleages.

I don't know what you mean by "faster" at floating point than
integer.

Maybe he meant FP ops have a longer latency than integer ops?
But it does not matter much since they are fully pipelined.

The last comment answered my question. Speaking of piplines, how long is
the pipline on these chips?

Grumble wrote:
Alex Johnson wrote:


Isaac Gerg wrote:


I heard a rumor that floating point operation the the 64bit
Itanium processors perform faster than integer operations. I
do not see how this is possible. Can someone enlighted me? I
would appreciate it. If this is not true, I want to put these
rumors to rest among my colleages.

I don't know what you mean by "faster" at floating point than
integer.


Maybe he meant FP ops have a longer latency than integer ops?
But it does not matter much since they are fully pipelined.

Isaac Gerg wrote:
The last comment answered my question. Speaking of piplines, how long is
the pipline on these chips?

Grumble wrote:

Alex Johnson wrote:


Isaac Gerg wrote:


I heard a rumor that floating point operation the the 64bit
Itanium processors perform faster than integer operations. I
do not see how this is possible. Can someone enlighted me? I
would appreciate it. If this is not true, I want to put these
rumors to rest among my colleages.


I don't know what you mean by "faster" at floating point than
integer.



Maybe he meant FP ops have a longer latency than integer ops?
But it does not matter much since they are fully pipelined.


Itanium (Merced): 10 stages
Itanium 2 (McKinley and Madison): 8 stages

--
My words are my own. They represent no other; they belong to no other.
Don't read anything into them or you may be required to compensate me
for violation of copyright. (I do not speak for my employer.)

Isaac Gerg wrote:

Speaking of pipelines, how long is the pipeline on these chips?

http://intel.com/design/itanium2/manuals/25111003.pdf
Itanium 2 Reference Manual for Software Development and Optimization
Appendix A - Itanium 2 Processor Pipeline

Listen up Intel: could you, please, allow content extraction on your
Itanium PDF documents?