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I have written a program that captures and displays video from three video cards. For every frame I spawn a thread that compresses the frame to Jpeg and then puts it in queue for writing to disk. I also have other threads that read from these files and decodes them in their own threads. Usually this works fine, it's a pretty CPU intensive program using about 70-80 percent of all six CPU cores. But after a while the encoding suddenly slows down and the program can't handle the video fast enough and starts dropping frames. If I check the CPU utilization I can see that one core (usually core 5) is not doing much anymore.
When this happens, it doesn't matter if I quit and restart my program. CPU 5 will still have a low utilization and the program starts dropping frames immediately. Deleting all saved video doesn't have any effect either. Restarting the computer is the only thing that helps. Oh, and if I set the affinity of my program to use all but the semi-idling core, it works until the same happens to another core. Here is my setup:
My app uses:
It seems to me like it would be some kind of problem with the way Linux schedules threads on the cores. Or is there some way my program can mess up so bad that it doesn't help to restart the program?
Thank you for reading, any and all input is welcome. I'm stuck :)
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Should I Enable All Cores? Your operating system and the programs you're running will use as many cores and processing power as they need. So, there's really no need to enable all the cores. For example, Windows 10 is configured to automatically use all the cores if the program you're running has this ability.
Windows should use all available CPU cores out of the box, no configuration needed. In any case, you can't use more cores than your computer has. If it is somehow not using all available cores, enabling them won't hurt anything.
First of all, make sure it's not your program - maybe you are running into a convoluted concurrency bug, even though it's not all that likely with your program architecture and the fact that restarting the kernel helps. I've found that, usually, a good way is a post-mortem debugging. Compile with debugging symbols, kill the program with -SEGV when it is behaving strangely, and examine the core dump with gdb.
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