INTEL PENTIUM II XEON (Performance)
What shall we expect from a Pentium II Xeon? Will it blow away all that we knew so far?
The answer is yes and no. In the first place it's got to be a 'no', since the Pentium II Xeon won't blow away the Pentium II at all on the usual platforms where the Pentium II is used so far. The CPU core of the Xeon is identical to the core of the Pentium II as well as the Celeron, so the difference is only produced by the different L2 cache. In single processing and single threaded applications the performance gain of a full speed L2 cache over the half speed L2 cache of the Pentium II is minimal. Thus we will hardly see any difference in ANY application under Windows 95 or Windows 98. These two toys OSes are a simple 'no-go' for the Pentium II Xeon, because none of them supports multi processing or multi-threading. It requires a multi processing 32 bit OS like Windows NT or UNIX to take the slightest advantage of Xeon. The full speed L2 cache can show its muscles only when both CPUs are working hard, so even in a multi-processing or multi-threading environment where the CPUs are idle for half or 30% of the time the difference between Pentium II and Pentium II Xeon will be very little.
That is why it takes well programmed multi-threaded workstation software to show the benefit of the Xeon in workstation environments. The performance gain through the second CPU can be between 30 and 95 %, but this 'can be' is valid for both, the Xeon as well as the Pentium II. Only heavy traffic on the memory bus will give the full speed L2 cache of the Xeon an advantage, so that dual Xeon system can be between 3 - 25% faster than a dual Pentium II system.
The story looks a lot different in server systems. Here the Pentium II cannot compete because it's not up to running in quad configurations anyhow. A heavily working server has always got full traffic on the memory and I/O buses. Here the Xeon shows its power. It scales almost linearly with the amount of CPUs used and whilst a Pentium II or Pentium Pro server shows a serious drop in TPS (transactions per second), the Xeon can still go ahead and kick some serious butt.
If you want to understand more about multi-processing and multi-threading, please have a look at this excellent paper from Intel.
I am very unhappy to let you know that I am still working on a server benchmarking setup and I'm also still waiting for several multi-threaded benchmarking software. Thus I had to come up with some own ideas on how to benchmark the Xeon CPU properly without this software. I will include server as well as workstation software benchmarks in the near future.
The used system consisted of the following components:
Winstone is a single threaded benchmark and thus doesn't show much of a difference between Pentium II and Pentium II Xeon. Viewperf is a single threaded OpenGL benchmark, which shows the same results as well.
The same with the new pre-release Diamond OpenGL power card, blowing away the results of the highly respected Fire GL 4000. The Xeon can show a bit of its strength here, but 1-2 % wouldn't be any reason for buying it over a Pentium II.
3D Studio Max is a well programmed multi-threaded application, which can benefit tremendously from a dual CPU system. However it doesn't push the memory bus to the edge, so that the difference between the two CPUs is very little again.
Trying to push the multi-tasking I let Winzip compress a 1.2 GB file with the highest compression whilst running High End Winstone 98. You can see that neither the Pentium II nor the Pentium II Xeon are impressed by the background file compression much. Try this on a single CPU system and you won't be able to run Winstone at all.
This one is really nasty. Running not only the Winzip file compression but also an AVI-video in the background whilst benchmarking with High End Winstone really pushes the multi-processing abilities of the CPUs to its limit. Here you can see a 16% advantage of Xeon over Pentium II. Xeon shows its superiority if there's really heavy traffic on the buses.
Running Xeon under Windows 95 is almost an insult, the difference is minimal.
Quake 2 also doesn't benefit of course.
On my way of trying to find a sensible benchmark that can show the advantage of Xeon over Pentium II I came across a lot of surprising occurrences. Running Quake 2 under NT in a dual Pentium II or Xeon system shows that you can run a file compression whilst playing Quake 2 online without ANY performance impact. Viewperf was also completely unimpressed by running in parallel with Winzip or the AVI-video, the scores stayed the same. I am running my own system with a dual PII 400 under NT and to the question why dual I always answer 'because I can record a CD and play Quake2 at the same time'. It is true, the main reason for a dual CPU system should be the usage of multi-threaded software. However, you can benefit from it even with single threaded software, in case you should have the strange habit of running several power hungry applications at the same time. Don't forget to put enough RAM into the system though!
Unfortunately I cannot offer you any server or workstation benchmarks yet. The setup for a decent server benchmark is scaringly big and I'm still waiting for the workstation software. I personally look forward to the Xeon benchmarking and evaluation of c't Magazine that will be available by this weekend. Andreas Stiller is still 'THE MAN' when it comes to CPU evaluations. I hope that I can at least put up a link to an article at the c't website. PC Professional's gem Kai Schmerer has the chance of using their big server lab, so that I'm looking forward to his evaluation as well. For now we have to go with Intel's own performance evaluations, but from what I see and hear the results are the same as seen outside of Intel.
One thing is clear, the Pentium II Xeon processor is NOT made for the masses. The design of the Xeon is focussed on multi-processing and multi-threaded applications, so that workstations can see a benefit of average probably about 10-15% over a Pentium II system, whilst Xeon servers will be able to really rock the boat. I am waiting for workstation benchmarks and then I will see if the investment of a Xeon over a Pentium II system makes sense to me at workstation level. I don't doubt that high performance servers will greatly benefit from the Xeon though, as long as all those bugs get sorted out.
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Articolo tratto dal sito www.tomshardware.com - 25/01/1999