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Subject: Re: IA-64 vs OOOE (attn Taylor, Hyatt)

Author: Tom Kerrigan

Date: 10:20:38 02/18/03

Go up one level in this thread


On February 16, 2003 at 00:04:34, Eugene Nalimov wrote:

>On February 15, 2003 at 21:37:19, Tom Kerrigan wrote:
>
>>On February 13, 2003 at 15:46:26, Eugene Nalimov wrote:
>>
>>>Some time ago I wrote in the (lost) thread: please compare Itanium2 not with
>>>P4/Athlon/etc., but with server CPUs. I.e. with 4-way Xeons, Power4, etc.
>>
>>I don't know how I got dragged into talking about x86 at all. Everybody seems to
>>assume that I want to prove that the P4 is better than the I2 in all cases no
>>matter what. The comparison I'm interested in is Opteron vs. I2...
>>
>>>benchmarks it resembles real-world server-like code a most: it's (relatively)
>>>large, execution time not spent in several functions but heavily spread across
>>>lot of functions, lot of loops across pointer chains, lot of calls,
>>>unpredictable branches, etc.
>>
>>In other words, it's suited to chips with lots of cache or low latency memory
>>and low branch mispredict penalties. Opteron addresses all of these issues.
>
>Why it should be better than Power4+?

Higher clock speeds (if not initially, shortly thereafter) and lower branch
mispredict penalties. (12 vs 17 stage pipeline.) Also, is the POWER4's memory
controller on-die or just in-package? If it's not on-die, that's a big memory
latency advantage for x86-64...

-Tom



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