并行计算速度反而慢了？

并行仿真prejects的例子coupling，电脑为P4双核2.8，内存为2G，每个cpu采用2线程，结果仿真的时间反而长了。由原来0.31秒变成0.94秒。

您的 CPU 行號是 ? P820嗎? 真正的雙核.應該不會如此.
http://www.feko.info/feko-product-info/technical/special-module-and-feature-articles/parallel-processing/parallel-processing
Parallel Processing
A short description of FEKO's parallel processing abilities.
Many modern computer systems make use of multiple processing units in order to improve computing performance. Such systems include:
simple multicore CPUs (i.e. one computer with one CPU having multiple cores),
multi-CPU PCs and SMP workstations (symmetric multiprocessor, typically 2 to 8 CPUs),
large massively parallel distributed systems with typically 128 to 1024 CPUs (which can again be multicore).
In order to gain the most benefit from the computational hardware, parallel versions of FEKO support state-of-the-art interconnect technologies like GigE, Myrinet, Infiniband or vendor proprietary interconnects like the SGI NumaFlex technology.
In FEKO all the solution phases for all the various numerical techniques have been parallelised, e.g. the ray-tracing for UTD, the MoM matrix setup and solution, the near- and far-field calculations and also seemingly simple things such as power loss computations.
We are very proud of the parallel efficiency of the MLFMM in FEKO. Even for this mathematically complex technique all the phases of the solution process (near-field matrix setup, aggregation, translation, disaggregation, pre-conditioning, iterative solution etc.) have been parallelised rigorously. The efficiency of the parallel implementation in FEKO is in the order of 80% to 95%, depending on the problem and the solution phase etc. This means that for a system with 32 processors the run-time would be approximately 26 times (0.8*32) faster than on a sequential run, i.e. a single processor.
Total run-time efficiency (all solution phases) for parallel MLFMM solution
of a problem with 3.18 million unknowns.

Intel Cluster Ready
The "Intel Cluster Ready" program facilitates easier design, build and deployment of cluster computers. Developers of cluster computing software (such as FEKO) can validate their software for use on standard Intel cluster environments and be certified as Independent Software Vendors (ISV) by Intel.
FEKO is dedicated to improving the performance of our software in cluster computing environments and work closely with Intel engineers in this endeavour. As such FEKO was certified as ISV by Intel in 2007 and may proudly brand our software with the Intel Cluster Ready logo. This means that FEKO customers can purchase an Intel Cluster Ready certified computer with the confidence that FEKO has been qualified on this computing environment and will work straight out of the box.
More information on the Intel Cluster Ready initiative is available on the Intel website.
Windows HPC Server Ready
Windows HPC Server provides a productive, cost-effective, and high-performance computing (HPC) solution that runs on x64-bit hardware.  In addition to supporting OpenMP, MPI, and Web Services, Windows HPC Server also supports third-party numerical library providers, performance optimizers, compilers, and a native parallel debugger for developing and troubleshooting parallel programs.
FEKO has been optimised for use on high performance parallel processing systems and as such it is important to FEKO to maintain compatibility with Microsoft's HPC Server.

不知道你的CPU是否为真正的双核，如果是以前号称的超线程的CPU，本身性能不会得到提升，只是在多任务的时候，反应会加快
而且你这个例子，其实没所谓并行效率，才0.几秒的例子，能看出什么啊，并行任务分配和通信的时间都远不止如此，换个大点的试试，还不行就是你的系统的问题了

cpu是P820。应该是选用的例子不适合用并行计算。换一个大型程序，并行计算可以提速。

intel高階的雙核(後面有EE的)才有HT.......像P-820好像就沒有這個功能.........
我的印象中這款 CPU 雖然在 windows xp 的工作管理員可以看到兩核...但是他不是真正的兩核.
所以假使您不是最近出的 雙核或 4 Core CPU ... 那就不需要在測試了..
因為問題的關鍵在於 CPU 本身 ...

也跟内存大小有关系吧

ham.. 假使在內存都足夠的狀況下.他使用了那個年代的 CPU 都會有此問題. 我們稱那個叫 假雙核.