Home/ Questions/Q 378737
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-12T14:49:25+00:00

I have c# Console app, Monte Carlo simulation entirely CPU bound, execution time is

  • 0

I have c# Console app, Monte Carlo simulation entirely CPU bound, execution time is inversely proportional to the number of dedicated threads/cores available (I keep a 1:1 ratio between cores/threads).

It currently runs daily on:

AMD Opteron 275 @ 2.21 GHz (4 core)

The app is multithread using 3 threads, the 4th thread is for another Process Controller app.

It takes 15 hours per day to run.

I need to estimate as best I can how long the same work would take to run on a system configured with the following CPU’s:

http://en.wikipedia.org/wiki/Intel_Nehalem_(microarchitecture)
2 x X5570
2 x X5540

and compare the cases, I will recode it use the available threads. I want to justify that we need a Server with 2 x x5570 CPUs over the cheaper x5540 (they support 2 cpus on a single motherboard). This should make available 8 cores, 16 threads (that’s how the Nehalem chips work I believe) to the operating system. So for my app that’s 15 threads to the Monte Carlo Simulation.

Any ideas how to do this? Is there a website I can go and see benchmark data for all 3 CPUS involved for a single threaded benchmark? I can then extrapolate for my case and number of threads. I have access to the current system to install and run a benchmark on if necessary.

Note the business are also dictating the workload for this app over the next 3 months will increase about 20 times and needs to complete in a 24 hour clock.

Any help much appreciated.

Have also posted this here: http://www.passmark.com/forum/showthread.php?t=2308 hopefully they can better explain their benchmarking so I can effectively get a score per core which would be much more helpful.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    tomshardware.com contains a comprehensive list of CPU benchmarks. However… you can’t just divide them, you need to find as close to an apples to apples comparison as you can get and you won’t quite get it because the mix of instructions on your workload may or may not depend.

    I would guess please don’t take this as official, you need to have real data for this that you’re probably in the 1.5x – 1.75x single threaded speedup if work is cpu bound and not highly vectorized.

    You also need to take into account that you are:
    1) using C# and the CLR, unless you’ve taken steps to prevent it GC may kick in and serialize you.
    2) the nehalems have hyperthreads so you won’t be seeing perfect 16x speedup, more likely you’ll see 8x to 12x speedup depending on how optimized your code is. Be optimistic here though (just don’t expect 16x).
    3) I don’t know how much contention you have, getting good scaling on 3 threads != good scaling on 16 threads, there may be dragons here (and usually is).

    I would envelope calc this as:

    15 hours * 3 threads / 1.5 x = 30 hours of single threaded work time on a nehalem.

    30 / 12 = 2.5 hours (best case)

    30 / 8 = 3.75 hours (worst case)

    implies a parallel run time if there is truly a 20x increase:
    2.5 hours * 20 = 50 hours (best case)

    3.74 hours * 20 = 75 hours (worst case)

    How much have you profiled, can you squeeze 2x out of app? 1 server may be enough, but likely won’t be.

    And for gosh sakes try out the task parallel library in .Net 4.0 or the .Net 3.5 CTP it’s supposed to help with this sort of thing.

    -Rick

    • 0