Rendering and HPC Benchmark Session Using Our Best Servers
by Johan De Gelas on September 30, 2011 12:00 AM ESTSTARS Euler3D CFD
The STARS Euler3D CFD benchmark got popular thanks to Scott of Techreport.com. It is a computational fluid dynamics (CFD) benchmark based on the STARS Euler3D structural analysis routines developed at CASELab, the Computational AeroServoElasticity Laboratory at Oklahoma State University. Since the benchmark has been used for years by Scott, we felt it was a good place to start our HPC benchmarking adventure: we could check if our results are in the right ballpark.
The benchmark is downloadable and described in great detail here. The benchmark score is reported as a CFD cycle frequency in Hertz, with higher results being better.
The Xeon E7 scales quite nicely on the condition that you disable Hyper-Threading. The benchmark is able to take advantage of Hyper-Threading, which can be seen on the dual Xeon system. However, the threads work on the same data grid, so the more threads, the more locking contention rears its ugly head. Here's a more detailed look at scaling with the number of threads:
The Hyper-Threading enabled Xeon X5670 performs worse than the non-HT setup until we run more than 12 threads. Once we do that it can offer a decent performance boost (17%). The benchmark however does not scale enough to take advantage of 80 threads. Hyper-Threading offers better resource utilization but that does not negate the negative performance effect of the overhead of running 80 threads. Once we pass 40 threads on the E7-4870, performance starts to level off and even drop.
Of course, you are probably more interested in the other server result. What happened to the Opteron scores? Why is the 48 core Opteron five times slower than the 40 core Xeon E7? Let's investigate further.
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jaguarpp - Friday, September 30, 2011 - link
what if instead of using a full program, create a small test program that is compiled for each platform something likedeclare variables int, floats, arrays to test diferent workloads
put the variables on loops and do some operation sum, div, the integers then the floats and so on measure the time that take to exit from each block
the hardest part will be how to make it threadable
and get acces to diferent compilers, maybe a friend?
anyway great article i really enjoy it even when i never get close to that class of hardware
thanks very much for the reading
Michael REMY - Friday, September 30, 2011 - link
very interesting analyze but...why use a score in cinebench instead a time render score ?Time result are more meaning for common and pro user than integer score !
MrSpadge - Friday, September 30, 2011 - link
Because time is totally dependent on the complexity of your scene, output resolution etc. And the score can be directly translated into time if you know the time for any of the configurations tested.MrS
Casper42 - Friday, September 30, 2011 - link
Go back to Quanta and see if they have a newer BIOS with the Core Disable feature properly implemented. I Know the big boys are now implementing the feature and it allows you to disable as many cores as you want as long as its done in pairs. So your 10c proc can be turned into 2/4/6/8 core versions as well.So for your first test where you had to turn HT off because 80 threads was too much, you could instead turn off 2 cores per proc and synthetically create a 4p32c server and then leave HT on for the full 64 threads.
alpha754293 - Sunday, October 2, 2011 - link
"Hyper-Threading offers better resource utilization but that does not negate the negative performance effect of the overhead of running 80 threads. Once we pass 40 threads on the E7-4870, performance starts to level off and even drop."It isn't thread-locking that limits the performance. It isn't because it has to sync/coordinate 80-threads. It's because there's only 40 FPUs available to do the actual calculations on/with.
Unlike virtualization, where thread locking is a real possiblity because there really isn't much in the way of underlying computations (I would guess that if you profiled the FPU workload, it wouldn't show up much), whereas for CFD, solving the Navier-Stokes equations requires a HUGE computational effort.
it also depends on the means that the parallelization is done, whether it's multi-threading, OpenMP, or MPI. And even then, within different flavors of MPI, they can also yield different results; and to make things even MORE complicated, how the domain is decomposed also can make a HUGE impact on performance as well. (See the studies performed by LSTC with LS-DYNA).
alpha754293 - Sunday, October 2, 2011 - link
Try running Fluent (another CFD) code and LS-DYNA.CAUTION: both are typically usually VERY time-intensive benchmarks, so you have to be very patient with them.
If you need help in setting up standardized test cases, let me know.
alpha754293 - Sunday, October 2, 2011 - link
I'm working on trying to convert an older CFX model to Fluent for a full tractor-trailer aerodynamics run. The last time that I ran that, it had about 13.5 million elements.deva - Monday, October 3, 2011 - link
If you want something that currently scales well, Terra Vista would be a good bet (although it is expensive).Have a look at the Multi Machine Build version.
http://www.presagis.com/products_services/products...
"...capability to generate databases of
100+ GeoCells distributed to 256 individual
compute processes with a single execution."
That's the bit that caught my eye and made me think it might be useful to use as a benchmarking tool.
Daniel.
mapesdhs - Tuesday, October 4, 2011 - link
Have you guys considered trying C-ray? It scales very well with no. of cores, benefits from as
many threads as one can throw at it, and the more complex version of the example render
scene stresses RAM a bit aswell (the small model doesn't stress RAM at all, deliberately so).
I started a page for C-ray (Google for, "c-ray benchmark", 1st link) but discovered recently
it's been taken up by the HPC community and is now part of the Phoronix Test Suite (Google
for, "c-ray benchmark pts", 1st link again). I didn't create C-ray btw (creds to John Tsiombikas),
just took over John's results page.
Hmm, don't suppose you guys have the clout to borrow or otherwise have access to an SGI
Altix UV? Would be fascinating to see how your tests scale with dozens of sockets instead of
just four, eg. the 960-core UV 100. Even a result from a 40-core UV 10 would be interesting.
Shared-memory system so latency isn't an issue.
Ian.
shodanshok - Wednesday, October 5, 2011 - link
Hi Johan,thank you for the very interesting article.
The Hyperthreading ON vs OFF results somewhat surprise me, as Windows Server 2008 should be able to prioritize hardware core vs logical ones. Was this the case, or you saw that logical processors were used before full hardware core utilization? If so, you probably encounter one corner case were extensive hardware sharing (and contention) between two threads produce lower aggregate performance.
Regards.