[FFmpeg-trac] #7582(undetermined:new): hwaccel cuvid/nvenc performance degredation when using aq (temporal-aq or spatial-aq) with multiple concurrent encodes

[FFmpeg]

#7582: hwaccel cuvid/nvenc performance degredation when using aq (temporal-aq or
spatial-aq) with multiple concurrent encodes
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             Reporter:  malakudi     |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  important    |                Component:
                                     |  undetermined
              Version:  git-master   |               Resolution:
             Keywords:  regresssion  |               Blocked By:
  cuda nvenc                         |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by malakudi):

 Made also tests on Quadro P2000 with drivers 390.87 (RTX 2080 tests were
 on 418.56 drivers) where I can run more than two instances. Results are
 different but still there is a big performance hit.

 1 instance => 578 fps
 1 instance with temporal-aq 0 => 604 fps
 1 instance with cuStreamSynchronize disabled => 600 fps
 2 instances => 2*229 => 458 fps
 4 instances => 4*114 => 456 fps
 8 instances => 8*57 => 456 fps
 16 instances => 16*27 => 432 fps
 16 instances with temporal-aq 0 => 16*37 => 592 fps
 16 instances with cuStreamSynchronize disabled => 16*37 => 592 fps
 24 instances => 24*17 => 408 fps
 24 instances with cuStreamSynchronize disabled => 24*24 => 576 fps

 With nvidia-smi dmon you can see in all tests above 1 session, that
 utilization is never 100% when using current git. Usage of
 cuStreamSynchronize hurts performance very much. As concurrent encoding
 sessions increase, the impact is larger.

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Ticket URL: <https://trac.ffmpeg.org/ticket/7582#comment:3>
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