Performance AMD Processor
Hello,
I am in front of an issue. I have an HP Proliant DL785 G6 (8x Sixcore AMD Opteron 8439-SE) at my disposal, and I ran several tests on it (OF on caelinux - Ubuntu 10.04) But unfortunately the performance are very disappointing in comparison with Intel Processors. Some results here: http://www.cfd-online.com/Forums/har...tml#post400039 In summary, a run on a HP-Z420 (Intel Xeon E5-1620 @ 3.6GHz) with 8 Cores (although this is a quadcore processor) is almost 3 times faster than same run on 26 cores (Proliant) Any idea? :rolleyes: |
Well, you are not really giving enough information. There are many things which can affect the results that you are getting. For one thing, small benchmark problems don't do well on many cores. You also cannot expect a 2009 era CPU to be competitive with a modern one, quite apart from the fact that the current generation Intel processors are particularly good. There have been big advances in memory architecture, for example. As a rule of thumb, my experience is that you do better with new low end hardware than obsolete heavy duty equipment.
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Thanks for answering.
I did benchmarks from 100K till 10 millions cells mesh, and watched especially speed up for my largest mesh. I am aware that there are many factors which may influence the speedup, but I always proceed in same maner each time I want to test a hardware: install caelinux, copy case, and run Now what you write makes also sense, but I never thought this Proliant was already obsolete. And more, the results on this Proliant are at same order than my OLD P4 Cluster (4x Intel P4 3.2GHz - 5x P4 3.0GHz - 2x P4 2.8GHz - 2x P4 2GHz - 1x P4 1GHz) with Gigabit/s switch. This last comparison is disturbing me |
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I agree
But it cannot be slower than a more older desktop cluster (4x Intel P4 3.2GHz - 5x P4 3.0GHz - 2x P4 2.8GHz - 2x P4 2GHz - 1x P4 1GHz), isn't it? |
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I'm on fire with advice today. :D On a serious note: you shouldn't be so surprised.. realize that the OLD Opteron (no matter how impressive 8 processors with 6 cores each might sound) is still built around several generations old architecture (45 nm) and uses DUAL CHANNEL DDR2 of all things. :) You could have 75 processors and they'd all still bottleneck at the goddamn dual channel DDR2. In fact, I'd bet it's not even DDR2-800 MHz, prolly some "server grade" slowpoke of 667 or even lower. Replace the dinosaur and have a nice day. |
And I thought my IT-department gave me something hot... :rolleyes:
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Haha, I don't want to mention what our current Sandy Bridge E cluster is doing with our older X5550 cluster - and that was pretty fast compared to the even older AMD cluster. It was just two or two and a half years between the purchase of each of them.
It's like seeing my "old" (2.5 years) 8-core workstation suffering benchmarks against a "new" (6 months) 6-core workstation, just because the CPU is faster for the newer one. And the 8-core (X5550) workstation is still almost twice as fast compared to my 4-core desktop (Phenom II 956) at home (when running both on 4 cores). So never underestimate how fast computer hardware can be outdated, even when it's not really old hardware. |
Greetings to all!
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Bruno |
Hello Bruno thanks for replying,
I will try to reply to each point: 1. For sure I dind't rebuild OpenFOAM from source, but I also didn't do it on the other machines (desktop). Worst : on the Intel Xeon E5-1620 (HP Z420) I couldn't install caelinux, so I only started on a old OpenSuse with old OF (OS installed for another old desktop; I mean I took the harddisk from old desktop and I placed it on Z420. Then boot and run...) 2. Yes I forgot to mention, that caelinux is installed on Virtual Machines (VM Ware) 3. 64 bit 4. I have no chance to do some tricks with BIOS on the server ( disinclined IT). The server isn't reserved only for CFD, and I don't know exactly what IT is doing with this server. Else for sure, I already would have installed latest Linux disto with latest OF (no VM) :rolleyes: |
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