10 May
2010
10 May
'10
8:19 p.m.
On May 10, 2010, at 11:09 PM, Patrick Finnegan wrote:
Sometimes! Also, don't forget that most (all?) x86 processors
spend the majority of their wall-clock time waiting for memory.
Running HPL on a modern x86 processor tends to disagree with you
(though
on the recent 6+ core chips, memory wait can be significant if you're
pushing all the cores).
You work in a supercomputer environment...you're running far more
modern stuff than most of the rest of the world. I'm talking about
the HT/Replay chips. Think 2.4GHz 32-bit Pentiums. Those are the
boxes that I see everywhere.
-Dave
--
Dave McGuire
Port Charlotte, FL
So I ask
again. What clock signal is this 2GHz refering to?
The x86 processors from Intel and AMD contain an internal PLL which
multiplies the external clock to produce an internal clock for the
processor pipeline. Most of the CPU core is running on that core
clock. (In the case of the Pentium 4 and derived processors, some
of it actually operates at twice the core clock.) Instructions take
a variable number of cycles to execute, but there are multiple
instructions "in flight" at any given time. The average number of
instructions executed per clock cycle is greater than one.