Replies to post #8270 on Advanced Micro Devices Inc (AMD)

[chipguy]

In this scenario the
app is a real cache-buster and spends its entire time waiting on small items from memory.

The real figures can be estimated from the graph on the next page. The I2 is actually much slower than the P4!

These two factors don't compute. The I2 has twice the memory bandwidth as a 2 GHz P4. Depending
on which machines they used to benchmark, the I2 would likely also had lower memory latency.

Also, the graph shows McKinley performing at around 1/4 the level of the EV7. Yet the EV7's STREAM
copy score is only 68% higher than McKinley's. I wonder what compilers they used for this exercise.

[Petz]

On Red Storm benchmarks, why should Itanium 2 1 GHz be over 5X faster than Itanium 1 733 MHz? (chart 53) Are the spec scores that different, in particular, the "Sam Key" code? The FMA3D code runs 3.5x faster on Itanium 2 1.5 GHz vs. Itanium 1 0.5 GHz, so the >5X ratio for 1 GHz vs 733 is mystifying.

Perhaps for Itanium 2 they hand-tuned the code in assembly language but never re-ran it for the Itanium 1?

Also, did anyone catch the reference to "AMD Hammer at 2.5 GHz" in chart 49?

I like the "Thor's Hammer" nickname.

Petz