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Thread: RaceRender not using all CPU to create video.

  1. #1
    Potential Tuner
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    Sep 2018
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    RaceRender not using all CPU to create video.

    I just built a new Ryzen 3900x and and RaceRender is only consuming ~20% CPU when creating video. On my old CPU, it didnt have a problem consuming 100% while rendering. I've got the 'Maximum CPU' option checked. Is there a way to get RaceRender to use more CPU? Is there a way to create the videos faster?

    I've included a screenshot so you can see the thread usage while creating the video.

    racerenderlowcpu.png

  2. #2
    Potential Tuner
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    Apr 2019
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    I have a similar issue. I went from a 6-core intel 8700K running at ~100% to a 12-core AMD 3900X running at ~60%. This dropped my testing video render from 28 minutes to 24 minutes. I believe one issue is that RR3 only is using about 12-14 threads instead of the possible 24 threads. So the software needs to catch up the increasing number of cores available in CPUs. However, 20% is low. I would check that your RAM is running at full speed and not the fall back default as that will slow down the new AMD processors.

    Note: I also have 64 GB RAM and am pulling the 2 input videos (rearview mirror setup) from one SSD and outputting to another SSD so other bottlenecks are unlikely.
    As another datapoint, Handbrake dropped from 55 min (6-core system ~100% CPU) to 35 min (12-core system ~95% CPU) for my test movie reencode to HEVC.
    Last edited by ScottSoapbox; 09-06-2019 at 01:02 PM.

  3. #3
    HPT Employee Weston@HPTuners's Avatar
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    Usually in these cases, the primary issue is a single-threaded bottleneck, such as waiting on file storage I/O, OS functions, or there are also a few things internal to RR that could be the culprit too... For the most part, we'll fire up as many threads as you have CPU cores (current max is 32 threads for core renderer), and try to use all of them, but there are always going to be some tasks that don't lend themselves to parallelization, or that have such small units of work that it would take more resources to manage splitting it up than to just do it on one core. While traditional video editors and encoding tools are able to make use of extensive optimizations and parallelization, RaceRender is compositing many things together, with the possibility of varying levels of transparency, so often times it just has to wait for some tasks to complete before it can start on others that could be impacted by its results. That doesn't mean it's perfect, though; there are still opportunities for further improvement that I'd like the pursue...