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When I'm downloading a file (torrent) and playing a video, my video will periodically freeze. The video uses the GPU and barely the CPU, the total CPU usage isn't anywhere near 50% when I'm doing these two activities.

I'm wondering what the bottleneck is, and if there is anything I can do to improve it. Reducing the download speed didn't seem to help.

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  • perhaps you should be asking how to identify the cause of a bottleneck? ... where is the video originating?
    – jsotola
    Sep 13, 2021 at 0:27
  • both are using the micro sd card
    – deanresin
    Sep 13, 2021 at 0:42
  • are you saying that the torrent is downloading to an SD card and the video is playing from the same SD card?
    – jsotola
    Sep 13, 2021 at 0:48
  • yes they are both using the same sd card. Maybe that is the bottleneck? I'm wondering now if I download to my external drive if it first gets buffered on the sd card.
    – deanresin
    Sep 13, 2021 at 0:55
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    What I meant was, if you were playing a video off the SD card and downloading a torrent to an external drive, the torrent data would not be buffered/cached on the SD card -- which AFAICT re-reading the question and previous comments was what you were asking in comment #4: "if I download to my external drive if it first gets buffered on the sd card" = No, or at least there is no need for that to happen (it's possible, of course, but I doubt very much the relevant software is implemented that way). Anyway, glad you found a solution.
    – goldilocks ♦
    Sep 23, 2021 at 14:07

2 Answers 2

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Virtually all modern torrent clients use some sort of internal caching to improve performance. If the cache is large, there will be a noticeable slowdown when it expires or is flushed.

Try running your torrent client with nice and try setting a smaller cache size with a shorter expiry time. If you primarily use the Pi for downloads, long expiry time is simply counter-productive.

There's also a cache setting in video players, if the bottleneck is the SD card then caching 10 or so seconds of video to RAM should help.

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  • My transmission-daemon is using a cache size of only 4MB by default.
    – deanresin
    Sep 13, 2021 at 16:59
  • Have you tried nice nevertheless?
    – Dmitry Grigoryev
    Sep 14, 2021 at 11:14
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The bottleneck was the SD card. When I used an external USB drive to download and play from, the stutters stopped.

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