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Author Topic: OpenCL Prefrence Settings: Intel i7-3770, AMD Radeon HD 7770 2GB  (Read 6018 times)

David Cockey

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OpenCL Prefrence Settings: Intel i7-3770, AMD Radeon HD 7770 2GB
« on: September 15, 2012, 07:28:38 AM »
I'm a new user of PhotoScan and I experimented to find the "best" settings for OpenCL with my hardware. Bottom line is performance is very close when OpenCL is turned on and number of active CPU cores is set to 4, 5, 6 or 7 for my 8 thread CPU. Execution time for "Build Geometry" is cut in half and "Total Performance" more than doubles. Now for some details.

PhotoScan 0.8.5 build 1423 (64 bit)

HP Pavillion H9
Motherboard: Petragon 2AD5, Intel Z75 chipset
CPU: Intel i7-3770 CPU, rated 3.4GHz (3.9GHz max observed), 4 cores / 8 threads
Graphics: AMD Radeon HD 3770, 2GB memory (HP version), 1000MHz, Capeverde 10 core processor
Memory: 12GB

I used the first 10 photos in the sample01 download set. Align Photos was run with Accuracy: High.
The bounding box was reduced to be tight to the statue and plinth. No masking was used.

The OpenCL settings box shows a maximum of 8 active CPU cores.

Build Geometry (Arbitrary, High) was run 28 times with various combinations of OpenCL off/on and number of active CPU cores.

Execution Time (seconds) and  Performance (million samples/sec) were recorded for Device 1 (CPU), Device 2 (Capeverde, graphics processor) and Total Performance. There was considerable variation in the total times for repeat runs with the same settings, up to 12%. Performance results were much tighter. Times given below are typical.

OpenCL,  Active CPU Cores, Time (sec), CPU (ms/s), GPU (ms/s), Total (ms/s)
Off, Any, 315, 130, 0, 130
On, 8, 219, 127, 80, 205
On, 7, 155, 127, 175, 302
On, 6, 158, 126, 187, 312
On, 5, 155, 124, 190, 315
On, 4, 150, 124, 192, 317
On, 2, 172, 108, 195, 303
On, 1, 214, 73, 200, 272
On, 0, 237, 0, 197, 197

Clearly turning OpenCL on and a setting for number of active CPU cores of 4 to 7 yields the best performance, with 4 slightly better than 5, 6, or 7.

The percent of utilization for the CPU cores was observed using Open Hardware Monitor and Windows Performance Monitor. The work was distributed across the cores regardless of the number of active CPU cores setting selected. This was true both with OpenCL on and off.
« Last Edit: September 15, 2012, 07:32:58 PM by David Cockey »

Wishgranter

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Re: OpenCL Prefrence Settings: Intel i7-3770, AMD Radeon HD 7770 2GB
« Reply #1 on: September 15, 2012, 01:28:46 PM »
Hello David, for monitoring of GPU, im suggesting you to use  http://www.ozone3d.net/gpushark/

there can see use of GPU, utilization of RAM and memory controler and etc. on gpu and other  useful info...
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bisenberger

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Re: OpenCL Prefrence Settings: Intel i7-3770, AMD Radeon HD 7770 2GB
« Reply #2 on: May 01, 2013, 07:09:41 PM »
Thanks for posting this David I was unclear as to how the CPU cores setting relate to the GPU.

Looks like OpenCL is only used when reconstructing depth...
« Last Edit: May 02, 2013, 12:23:15 AM by bisenberger »
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