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Author Topic: Negligible GPU usage on Alignmnet.  (Read 2804 times)

KDSTanhope

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Negligible GPU usage on Alignmnet.
« on: August 13, 2020, 10:29:55 AM »
HI Alexy and team.

Our workstation has, in recent updates, stopped using the GPU, from what I can tell.

System:
TR 2920X
64 GB RAM
RTX 2080 ti
4 x 4TB RAID0

Metashape:
1.6.4

Process:
AlignPhotos: accuracy = High, preselection = generic, reference, keypoint limit = 80000, tiepoint limit = 4000, apply masks = 0, filter tie points = 0, adaptive fitting = 0

While the console window indicates that the GPU is being used to find matching image points, GPU-Z and windows system monitor both indicate that the GPU is idling at ~1%. Disk usage is high.

Console:
Code: [Select]
Detecting points...
Found 1 GPUs in 0.001 sec (CUDA: 0.001 sec, OpenCL: 0 sec)
Using device: GeForce RTX 2080 Ti, 68 compute units, free memory: 9185/11264 MB, compute capability 7.5
  driver/runtime CUDA: 11000/8000
  max work group size 1024
  max work item sizes [1024, 1024, 64]
[GPU] photo 4146: 80000 points
[GPU] photo 4246: 80000 points
[GPU] photo 4346: 80000 points
[GPU] photo 4446: 80000 points
[GPU] photo 51: 80000 points
etc...

During this time the CPU load is average at 20% and the GPU load is 0-1%.

Use GPU is turned on in the settings, use CPU during GPU is turned off.

I'm at a bit of a loss and somewhat worried the enormous hardware investment was a wasted effort given that the older hardware ran considerable faster with a considerably lower overhead.

KDSTanhope

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Re: Negligible GPU usage on Alignmnet.
« Reply #1 on: August 13, 2020, 05:14:42 PM »
A bit of an update from my end:

The process of detecting new points does not appear to use the GPU.

6 hours of detecting new points where neither the GPU nor the CPU were doing much of anything has me a little concerned that the bottleneck may be the drive read/write speeds.

In any case, the process of "Matching Points" does indeed load the GPU to ~100%.

Is this expected behaviour?

Arie

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Re: Negligible GPU usage on Alignmnet.
« Reply #2 on: August 13, 2020, 09:04:01 PM »
Hi,
I just tested it and on my system, GPU usage jumps between 0-37% during feature detection (GPU-Z).
Images and project files on 2x 1TB Raid0 Samsung 970 Evo Plus, GPU 1080TI, CPU 3960X.
Hope that helps?!
Cheers

tutoss

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Re: Negligible GPU usage on Alignmnet.
« Reply #3 on: August 13, 2020, 11:17:14 PM »
Also "low" gpu usage (see attached image) on two 2080 super and one 1070.
Anyway, 7 minutes for "detecting points" for 843 photos, is very good! 

I tested with all gpu disabled, and the time for run "detecting points" is about 32 minutes (AMD TR 2950X).
With one 2080 super, the time is 7,5 minutes (the true power of 3 gpu is much more noticeable on other stages).

Metashape 1.6.3

You can try benchmarking with all gpu disabled and share the results.

Regards,

Tutos
« Last Edit: August 13, 2020, 11:55:07 PM by tutoss »

KDSTanhope

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Re: Negligible GPU usage on Alignmnet.
« Reply #4 on: August 14, 2020, 09:11:57 AM »
Thank you guys, this is helpful.

This particular block is comprised of ~4000 medium format images as an added bit of info.

In the preferences>advanced>tweaks section there is an option, "main/refine_max_gpu_multiplier" which has a value of 2. I cannot find any documentation on this anywhere. Any ideas as to what it does?

tutoss

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Re: Negligible GPU usage on Alignmnet.
« Reply #5 on: August 14, 2020, 08:35:57 PM »
Thank you guys, this is helpful.

This particular block is comprised of ~4000 medium format images as an added bit of info.

In the preferences>advanced>tweaks section there is an option, "main/refine_max_gpu_multiplier" which has a value of 2. I cannot find any documentation on this anywhere. Any ideas as to what it does?

Which is your photos resolution?
My times for "detecting points" are with 21MP photos (5472x3648), Phantom 4 rtk.
I tested with a similar project (3500 images), with one 2080 Super, and the time to finish "detecting points" is ~27 minutes.
Without GPU, the time up to ~1 hour 50 minutes.

We have similar CPU and GPU, and you says your time is 6 hours for 4000 images!!! or the image resolution is very very high or something more is happening.

About "refine_max_gpu_multiplier" i don't know, the only thing i change on metashape are enable all GPU and turn off the CPU for GPU usage.

Regards,

Tutos.

« Last Edit: August 15, 2020, 12:19:17 AM by tutoss »

KDSTanhope

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Re: Negligible GPU usage on Alignmnet.
« Reply #6 on: August 15, 2020, 06:40:12 PM »
Thanks, Tutos.

The images are not enormous but they are 16-bit. Just shy of 50MP, they are about 5500 x 8500 and some change.

There are also TWO cameras, so that will add time too... but not as much as I am seeing here.

So there is definitely something amiss and I wonder how much of it is simply down to the additional camera and additional frame size & bit depth combination?


tutoss

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Re: Negligible GPU usage on Alignmnet.
« Reply #7 on: August 15, 2020, 10:07:54 PM »
Well, 50mp are pretty big hehe, plus they are 16bit.
about the two cameras, in this step (detecting points) is irrelevant.
If you wish, you can send me a small dataset (~200 images maybe) to benchmark the times with and without gpu (remember we have "similar" cpu and gpu).

Regards,

Tutos