LINPACK: Intel's Nehalem versus AMD Shanghai
A "beta BIOS update" broke compatibility with ESX, so we had to postpone our virtualization testing on our quad CPU AMD 8384 System.
So we started an in depth comparison of the 45 nm Opterons, Xeons and Core i7 CPUs. One of our benchmarks, the famous LINPACK (you can read
all about it here) painted a pretty interesting performance picture.
We had to test with a matrix size of 18000 (2.5 GB of RAM necessary), as we only had 3 GB of DDR-3 on the Core i7 platform. That should not be a huge problem as we tested with only one CPU. We normally need about 4 GB for each quadcore CPU to reach the best performance.
We also used the 9.1 version of Intel's LINPACK, as we wanted the same binary on both platforms. As
we have show before, this version of LINPACK performs best on both AMD and Intel platforms when the matrix size is low. The current 10.1 version does not work on AMD CPUs unfortunately.
We don't pretend that the comparison is completely fair: the Nehalem platform uses unbuffered RAM which has slightly lower latency and higher bandwidth than the Xeon "Nehalem" will get. But we had to satisfy our curiousity: how does the new "Shanghai" core compare to "Nehalem"?
Quite interesting, don't you think? Hyperthreading (SMT) gives the Nehalem core a significant advantage in most multi-threaded applications, but not in Linpack: it slows the CPU down by 10%. May we have found the first multi-threaded application that is slowed down by Hyperthreading on Nehalem? That should not spoil the fun for Intel though, as many other HPC benchmarks show a larger gap. AMD has the advantage of being first to the market, Nehalem based Xeons are still a few months away.
Also, the impact of the memory subsystem is limited, as a 50% increase in memory speed results in a meager 6% performance increase. The Math Kernel Libraries are so well optimized that the effect of memory speed is minimized. This in great contrast to other HPC applications where the tripple channel DDR-3 memory system of Nehalem really pays off. More later...
Then you can't afford enough DDR3.
Nobody seems to know if bozo turbo is off.
You don't know that a real IT would not use turbo.
Your readers all hate you for being so smug.
You have reinforced why I don't come here anymore.
You are conning and lying about AMD.
You use pro-Intel conditions and pretend you are fair.
You discredit a very detailed test posted with real facts and also it bears the names of the testers - and their source. That test, in the 'comments' is far better than anything on this website.
You insult people who refuse to consume the manure you spread.
You treat us all like mushrooms.
You will refute all of the above.
In short, you suck so bad.
ANYONE SEEKING REAL INFO RE AMD SERVERS OR DESKTOPS GOTO AMDZONE.
and if I wanted to know about intel I would not come here for that either.
Do you actually expect any better treatment than this?
I am sure also that you will tell us all that
the i7 TLB BUG IS JUST OK TOO.
You will probably del this post. Like I care. Ship of fools.