As we mentioned previously, upcoming FluidMark 1.2, next version of popular GPU PhysX testing and benchmarking application, will include support for Multi-Core CPU PhysX calculations, and overall multi-threading optimizations as well.
Jerome Guinot, FluidMark developer, was kind enough to provide us with latest beta-version of new Fluid-Mark 1.2, and we’ll try to answer finally, what is faster – GPU PhysX or properly optimized CPU PhysX.
Main control panel now includes several additional options, like “Force PhysX CPU” – ability to switch between GPU and CPU PhysX, without necessity to use Nvidia Control Panel.
“Multi-core PhysX” checkbox enables all multi-threading optimizations, vital and most interesting part of new FluidMark.
“# of CPU cores” is used specify number of CPU cores dedicated to simulation (up to 32 in current version), however this option is no so transparent as it looks – increased number of cores adds additional fluid emitters to the scene (one emitter per core or two in general), and with equal number of particles, various number of emitters can affect performance.
Application window has also changed – benchmark is still based on SPH fluid simulation, buit into PhysX SDK (latest version 2.8.3.21 is used), but scene includes additional static objects, particles appearance if different and, as mentioned earlier, several emitters can be used simultaneously. Nice addition – GPU temperature overlay, usefull for GPU stress testing.
Final Global score in benchmarking mode is calculated now in a different way, and can’t be compared with previous version of FluidMark. It consist of two components – GraphX score (graphics framerate per second) and PhysX score (physics simulations per second).
Thus, Global score = (GraphX_score * 0.3 + PhysX_score * 1.7) / 2
Now, lets do some testing.
Take a look at the following graph:
[Three emitters were used (# CPU cores = 4) with fixed number of particles - 15 000. Timerange - 60 sec. 800x600 rendering window. System: C2Q 9400 @ 2.66 GHz CPU, Nvidia GTX 275 + GTX 260 (192 sp) GPUs, 4GB RAM, Win XP, PhysX System Software 9.09.1112]
When “Multi-core PhysX” option is off, PhysX simulation and scene rendering are done in the same thread and, more important, PhysX SDK multi-threading flags are not set.
But when “Multi-core PhysX” is enabled, all PhysX simulations are done in separate threads and since there is still a thread for the rendering, scene rendering is boosted because there is no longer PhysX in scene thread. Same situation with PhysX, one or several threads are completely dedicated for physics simulation.
While SPH fluid simulation is running on CPU with “Multi-core PhysX” set to off, load is destributed through several cores (probably due to internal Windows threads management), but in sum that’s 26% – full one core.
But with multi-threaded optimizations enabled, application fully utilizes all four cores by 100%, what results in great speed boost.
In addition, one interesting detail was discovered – fluid simulation is running faster on GPU when one emitter is used, and opposite way – for CPU it prefers multiple emitters (with equal number of particles) – probably that’s peculiarity of PhysX SDK itself.
For example, with one emitter and multi-core PhysX switched to off, CPU simulation results in 36 global points (64 with 3 emitters – on graph above), while GTX 275 GPU – in 247 points (128 with 3 emitters). But since one emitter can’t utilize more than two cores, number of emitters was increased to gain equality.
Therefore, bechmarking seems to be a little tricky in new FluidMark. We are curious if someone will come with solid method after app release.
P.S. Thanks to Jerome for beta FluidMark and detailed explanations 
不知道，同样离奇的是Multi-core PhysX Off下，CPU+GPU相对GPU几乎没有增长
PS：我记得以前哪位大大说 ...
纳尼？ 发表于 2010-3-18 23:36
回复 nfsking2
显然FluidMark是通过特殊手段破解而达到了取消某些限制的，只要有功能这中破解对于程序 ...
ArthurMa 发表于 2010-3-19 00:41
I’m currently updating Geeks3D’s PhysX FluidMark tool and from my last tests, multi-core CPU support in PhysX seems to be ok (that confirms what NVIDIA said in this news)…
Here is the reply of Nadeem Mohammad, NVIDIA’s PhysX director of product management, to AMD’s accusations:
I have been a member of the PhysX team, first with AEGIA, and then with Nvidia, and I can honestly say that since the merger with Nvidia there have been no changes to the SDK code which purposely reduces the software performance of PhysX or its use of CPU multi-cores.
Our PhysX SDK API is designed such that thread control is done explicitly by the application developer, not by the SDK functions themselves. One of the best examples is 3DMarkVantage which can use 12 threads while running in software-only PhysX. This can easily be tested by anyone with a multi-core CPU system and a PhysX-capable GeForce GPU. This level of multi-core support and programming methodology has not changed since day one. And to anticipate another ridiculous claim, it would be nonsense to say we “tuned” PhysX multi-core support for this case.
PhysX is a cross platform solution. Our SDKs and tools are available for the Wii, PS3, Xbox 360, the PC and even the iPhone through one of our partners. We continue to invest substantial resources into improving PhysX support on ALL platforms–not just for those supporting GPU acceleration.
As is par for the course, this is yet another completely unsubstantiated accusation made by an employee of one of our competitors. I am writing here to address it directly and call it for what it is, completely false. Nvidia PhysX fully supports multi-core CPUs and multithreaded applications, period. Our developer tools allow developers to design their use of PhysX in PC games to take full advantage of multi-core CPUs and to fully use the multithreaded capabilities.
回复 nfsking2
这位NV PhysX的负责的说明其实是从某种层面可以看作影射了之前的问题.
至于将Multi t ...
ArthurMa 发表于 2010-3-19 09:38
bc2的物理效果，我看还不如红色派系。
westlee 发表于 2010-3-19 12:57
回复 nfsking2
蟑螂理论是针对有人把事情归咎于游戏开发商，而非FluidMark 1.2，希望看清我说的话.
ArthurMa 发表于 2010-3-19 12:01
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