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Simulink simulation slows down drastically after first run following reboot

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MP
MP 2018 年 3 月 29 日
回答済み: MP 2018 年 4 月 2 日
Hi! I am having an issue with a simulink simulation. The first time I run it after a windows reboot, the simulation rate is somewhere around 0.7 simulation seconds / real seconds. When I simulate again, the simulation rate drops to about 0.1 simulation seconds / real seconds. Subsequent runs slow down further and stabilize somewhere around estimated 0.02 simulation seconds / real seconds. For a simulation that needs to simulate 150 seconds to be meaningful, this is far too slow. Since I cannot publicly post this simulation, I will describe properties of the simulation, as well as observations I have made regarding this issue.
Description of simulation:
  • Heavily using Simscape Power Systems -> Specialized Technology
  • Discrete fixed-step solver (auto-select), no continuous states
  • Rapid-accelerator mode (though this also seems to happen when using normal mode)
  • most parameters are defined using a struct "par" in the base workspace. Simulink blocks are parameterized by accessing this struct (e.g. a constant value would be set by entering "par.someConstantValue").
  • There is a use of masked and variant subsystems
Computer info:
  • Windows 10 64-bit
  • 32GB of ram (absolutely not limiting for the case I'm describing here)
  • Core i7-8700K
  • Geforce 1060
Observations:
  • This issue likely exists/has become severe since I ran this simulation overnight for a long time with lots of output data. It probably was too much data. The computer had crashed the next day I came back to it. This was using Matlab 2017b
  • I thought I might as well update to Matlab 2018a afterwards. No difference for this issue, though.
  • Another simulation shows the same slow-downs. It is based on the Simscape Power Systems example "Thyristor-Based HVDC Transmission System (Detailed Model)". As soon as I change the parameterization to the struct-model described above, simulation performance drops by a few orders, but remains stable. Therefore, I am not really sure if this is the core of the problem.
I do not know where to look and what else to try. I have sunk a lot of time into this already and need to become productive again. I am going to test this on another computer, as soon as I can. Does anyone have any help/clues/support?
Thank you very much! MP
Edit: please see second answer posted for further information.

回答 (3 件)

Ilham Hardy
Ilham Hardy 2018 年 3 月 30 日
Since you run the model in Rapid Accelerator mode, have you tried deleting the slprj and yourmodelname.mexw64?
  1 件のコメント
MP
MP 2018 年 3 月 31 日
Hi Illham, thank you for your reply. I did try this and it has no effect on the situation. I will post a more elaborate answer below in a few moments.

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MP
MP 2018 年 3 月 31 日
I did some systematic testing with lots of windows/matlab/simulation restarting tonight (18 test runs). Observations are as follows:
  1. The slprj and mexw64 do not seem to be connected to this issue
  2. I get one fast (0.7) run after a windows reboot. The next run will be slower (0.1, usually stabilizes somewhere around there for consecutive runs without any restarts)
  3. If I alter my parameter struct (par), the simulation speed will drop to super-slow (the 0.02 mentioned above). This can ONLY be reset by a windows restart. Even restarting matlab does not change this
  4. I saw that a new nvidia graphics driver was released 3 days ago (version 391.35). So I updated from the previous version (391.24). After that, the simulation slowing was a little less (maybe settling between 0.03-0.05 instead of 0.02). However, everything else is still unchanged, especially the way it slows down.

MP
MP 2018 年 4 月 2 日
I cannot reproduce this problem on a different computer (unfortunately much slower), hence it must be related to some OS, driver or configuration thing on this computer.
Nevertheless, I switched to the 'Accelerator' mode and don't seem to be having this issue. I will continue using this mode from now on.

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