Replies to post #47001 on Advanced Micro Devices Inc (AMD)

[dacaw]

Cache usage on specfp

Uh, your link points to memory, not cache usage. The executing portion of the program << total program size.

See how the itanic2 scales with cache (from spec site):

Dell Dell PowerEdge 3250 (1.4GHz/1.5MB, Itanium2) 1 256KB(I+D) on chip 1.5MB (I+D) on chip 1444 1444 Sep-2003
Dell Dell PowerEdge 3250 (1.4GHz/3MB, Itanium2) 1 core, 1 chip, 1 core/chip 256KB(I+D) on chip 3MB (I+D) on chip 1868 1868 Apr-2004
Dell Dell PowerEdge 3250 (1.5GHz/6MB, Itanium2) 1 256KB(I+D) on chip 6MB (I+D) on chip 1875 1875 Aug-2003

So at the same clock (1.4GHz) the fp score goes up > 400points as we double the cache from 1.5MB to 3MB!
Now increase the clock to 1.5GHz and double the cache to 6MB and the score goes up 7 (yes that's SEVEN) points.

Duh, doesn't that look like the score is highly cache sensitive with a used cache size somewhere between 1.5 and 3MB?? Once the app is bigger than the cache I suggest that the 1444 score is the accurate figure (add another seven on for the clock speed, say 1451).

At 1451 its a bit inferior to the Athlon64s as you no doubt realize. Typical results for the Opteron 150 run 1528-1644 with a 1MB cache.