I think there is some confusion about the IPC's of different processors. I think a simple article would be useful. Here is what I have come up with, but I think I may be wrong.
P4 IPC = 6
Intanium 2 IPC = 6
Athlon XP IPC = 9
K8 IPC = 10+
Sources: Athlon XP & P4
Source: Itanium 2
Source K8
P4 IPC = 6
Intanium 2 IPC = 6
Athlon XP IPC = 9
K8 IPC = 10+
Sources: Athlon XP & P4
http://www.active-hardware.com/english/reviews/processor/xp-2100.htmStill, even with that in mind, it's obvious that clock-frequency
isn't the sole deciding factor in system performance. If it was, the
P4 would have crushed the XP in the marketplace long ago. In reality,
the number of instructions a CPU can actually complete per cycle
(expressed as "IPC") is just as important as the number of cycles it
goes through in a second. The Pentium 4, with its ultra-long
hyperpipeline, is able to achieve astronomic clock frequencies, but
at the price of lower IPC performance. The Athlon XP, on the other
hand, goes through fewer cycles per second, but manages to get more
work done on each pass -- 9 instructions per cycle, as opposed to the
P4's 6 -- giving it a 150% advantage in IPC.
Source: Itanium 2
http://www.hp.com/products1/itanium/performance/index.htmlThe Intel Itanium 2 processor is able to issue instructions at a
peak rate of six instructions per cycle, and is equipped with
hardware resources to ensure a sustained throughput that is closer to
this maximum. It has leading price performance, especially when
combined with the HP zx1 Chipset, which is a high bandwidth,
low-latency chipset designed to be cost-efficient.
Source K8
http://www.chip-architect.com/news/2002_06_24_Hammers_Two_Extra_PipelineStages.htmlThe upcoming AMD Hammer family promises a significant increase in
performance compared with the current generation of Athlon
processors. Some of the increase comes from the low latency on chip
memory controller, some of it comes from the extra architectural
registers of the x86-64 instruction set and some comes from a number
of new features that improve the ability of the Hammer
micro-architecture to recognize a higher IPC ( Instructions executed
Per Clock) than previous generation micro-architectures. Here we look
into some depth into the latter.