[FFmpeg-user] High CPU usage during scale_npp to low resolutions with multiple instances

Valentin Schweitzer vs at nativewaves.com
Wed Apr 8 15:23:10 EEST 2020

Set this environment  variable: CUDA_DEVICE_MAX_CONNECTIONS=2

Then retest and report back.

One more thing: Could you show us the output of:

numactl --hardware

Thanks for your reply. We should have clarified that we are on Windows.
Unfortunately, setting the environment variable CUDA_DEVICE_MAX_CONNECTIONS
to 2 does not make a difference. The closest we got to a numactl equivalent
on Windows is the NUMA view in the Task Manager which shows four NUMA nodes
on our 24-core processor. Given this information, is it possible that either
the Windows scheduler or the NVIDIA driver is having troubles with different
ffmpeg instances being distributed to different NUMA nodes so that a lot of
data has to be transferred between NUMA nodes, limiting the CPU? Are there
any mitigations to this or is there anything else that we can analyze to
clarify why different resolutions behave so differently on our machine?


More information about the ffmpeg-user mailing list