Using Accelerad's rtrace.exe for irradiance calculation does not decrease calculation time

[ankujawa]

Hi all,
I am currently investigating options to decrease the run time of my bifacial_radiance simulations and I was wondering if there is a way to do the irradiance calculations via the GPU based Accelerad rtrace.exe.

Accelerad is supposed to do GPU based calculations by replacing Radiance's original rtrace and rpict functions. Since bifacial_radiance calls Radiance rtrace.exe I thought it is sufficient to replace the binariaries of my Radiance installation with the ones from Accelerad.

However comparing directly run times using bifacial_radiance with the original Radiance rtrace and the Accelerad rtrace shows no improvement of the execution time.

I am running the simulations on a Windows computer for the original Radiance installation and on a Linux machine for the version with the binaries from Accelerad. Both are running without a problem. The Windows computer has a 11th Gen Intel(R) Core(TM) i7-1185g7 @ 3.00GHz with 4 cores, no GPU. The Linux computer has a NVIDIA Tesla M10 with 5 multiprocessors.

The Windows simulation of 3 timestamps takes 7 minutes, on Linux the same simulation takes 8:45 minutes. When calling nvidia-smi -l 10, the output shows that the GPU is used by rtrace but only a small fraction of the available memory is used.

+-----------------------------------------------------------------------------+
| NVIDIA-SMI 525.85.12    Driver Version: 525.85.12    CUDA Version: 12.0     |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|                               |                      |               MIG M. |
|===============================+======================+======================|
|   0  Tesla M10           On   | 00000000:0B:00.0 Off |                  N/A |
| N/A   47C    P0    41W /  53W |    708MiB /  8192MiB |    100%      Default |
|                               |                      |                  N/A |
+-------------------------------+----------------------+----------------------+

+-----------------------------------------------------------------------------+
| Processes:                                                                  |
|  GPU   GI   CI        PID   Type   Process name                  GPU Memory |
|        ID   ID                                                   Usage      |
|=============================================================================|
|    0   N/A  N/A    691523      C   rtrace                            705MiB |
+-----------------------------------------------------------------------------+

I appreciate any help!