Rendering and HPC Benchmark Session Using Our Best Serversby Johan De Gelas on September 30, 2011 12:00 AM EST
Introduction to Server Benchmarking
Each time we publish a new server platform review, several of our readers inquire about HPC and rendering benchmarks. We're always willing to accommodate reasonable requests, so we're going to start expanding beyond our usual labor intensive virtualization benchmarks. This article is our first attempt. It was a bumpy ride, but this first attempt produced some very interesting insights.
The core counts of modern servers have increased at an incredible pace, making many benchmarks useless if we want to assess the maximum throughput. Just three years ago, we could still run benchmarks like Fritz Chess, Winrar, and zVisuel to satisfy our curiosity. We also performed real-world benchmarks like MySQL OLAP on our octal-core servers. All these benchmarks are pretty useless now on our 48-core Magny-Cours and 80-thread Westmere-EX systems. The number of applications that can really take advantage of the core counts found in quad- and even dual-socket servers continues to get lower and lower.
Most servers are now running hypervisors and virtualization of some form, so we naturally focused on virtualized environments. However, many of our readers are hardware enthusiasts, so while we wait for the new server platforms such as Intel's Romley-EP (Sandy Bridge EP) and AMD's Interlagos (Bulldozer) to appear, we decided to expand our benchmark suite. Our first attempt is not very ambitious: we'll tackle Cinebench (rendering) and Stars Euler 3D CFD (HPC). Both are quick and easy benchmarks to perform... or at least that'ss what we expected going in. On the plus side, our testing results are a lot more interesting than we imagined they would be.
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jaguarpp - Friday, September 30, 2011 - linkwhat if instead of using a full program, create a small test program that is compiled for each platform something like
declare 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 - linkvery 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 - linkBecause 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.
Casper42 - Friday, September 30, 2011 - linkGo 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 - linkTry 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 - linkI'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 - linkIf 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.
"...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.
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.
shodanshok - Wednesday, October 5, 2011 - linkHi 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.