!!!The Ultimate K8L Thread 2007 & Beyond!!!

[JumpingJack]

Really ? Not even Conroe manages 1-1.2 except on few codes.

P4 was around 0.3-0.7 and K8 0.5-0.9 at least for SPEC IIRC.

I don't know why 0.9 to 1.2 keeps sticking in my head, but in some code base yes, P4 could do that 0.9 to 1.2 (some apps within the SPECINT bench showed this high):

http://www.princeton.edu/~jdonald/re...uck_pact03.pdf

The benchmarks that perform
best in this environment are mcf, art and swim at 93%, 97%
and 98% of peak respectively. eon and wupwise have relatively
high instruction throughput of 0.9 and 1.2 IPC respectively,
while mcf and swim have relatively low IPCs of .08,
.2 and .4 (all IPCs measured in ��ops). Not unexpectedly,
then, those applications with low instruction throughput demands
due to poor memory performance are less affected by
the statically partitioned execution resources. See Figure 1
for a summary of results from these runs.

(EDIT: it is reading this paper sometime ago that 0.9 to 1.2 sticks in my head, because my first thought was wow... a P4 can actually do that )..

The IPC, of course, is very code dependent (compiler optimizations, instruction ordering, etc) and how the architecture handles the ILP efficiency, combined with all sorts of factors. Truth is I have looked over probably half dozen to dozen papers where the IPC is measured/calculated, HT helps, I have seen IPC as high as 1.6 in some code base. However, the original point is that it really really stunk in a general sense.... a long pipeline with unoptimized code for that situation will generally crater the efficiency.

Another example of who well and poor the P4 can do IPC wise:
http://www.geocities.com/ykchen913/p...ions/CAECW.pdf

In h.264, the IDCT chain could get as high as 1.16 (see table 4). This is a good paper, as it also shows FSB utilization on a P4 is quite low even with a high L2 miss rate.... this is on a 533 MHz FSB .... and multimedia is likely to have the highest demand on FSB.

Anyway, C2D I do believe is significantly higher than 1.0 IPC on average (some will be low of course, but others high), but I have not found any studies or data that has measured it.

Barcelona appears to be heading for a good IPC boost, achieving something higher that C2D will be a true accomplishment, C2D did a good job in this department to show the improvements. I am anxious to see the data.

Jack