Hi! Even if there is need to have a syncronization before leaving the ffmpeg call, callin cuMemcpyAsync will allow the copies to overlap with any other task on the gpu, that was enqueued using any other non-blocking cuda stream. That’s exactly what we want to achieve.
This would benefit automatically any other app that uses non-blocking cuda streams, as independent cuda workflows. Oscar Enviat des del meu iPhone El 7 maig 2018, a les 13:54, Timo Rothenpieler <t...@rothenpieler.org> va escriure: >>> Additionally, could you give your opinion on the feature we also may > want to add in the future, that we mentioned in the previous email? > Basically, we may want to add one more CUDA function, specifically > cuMemcpy2DAsync, and the possibility to set a CUStream in > AVCUDADeviceContext, so it is used with cuMemcpy2DAsync instead of > cuMemcpy2D in "nvdec_retrieve_data" in file libavcodec/nvdec.c. In our > use case this would save up to 0.72 ms (GPU time) per frame, in case of > decoding 8 fullhd frames, and up to 0.5 ms (GPU time) per frame, in case > of decoding two 4k frames. This may sound too little, but for us is > significant. Our software needs to do many things in a maximum of 33ms > with CUDA on the GPU per frame, and we have little GPU time left. >> >> This is interesting and I'm considering making that the default, as it >> would fit well with the current infrastructure, delaying the sync call >> to the moment the frame leaves avcodec, which with the internal >> re-ordering and delay should give plenty of time for the copy to finish. > > I'm not sure if/how well this works with the mapped cuvid frames though. > The frame would already be unmapped and potentially re-used again before > the async copy completes. So it would need an immediately call to Sync > right after the 3 async copy calls, making the entire effort pointless. > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel