Agisoft Metashape

Agisoft Metashape => General => Topic started by: mitchfx on May 04, 2014, 02:52:19 AM

Title: OpenCL Cores Enabled vs CPU Disabled?
Post by: mitchfx on May 04, 2014, 02:52:19 AM
I am a bit confused about the correct settings for disabling CPU cores when OpenCL devices are in use.  In your help file you state that one CPU core should be disabled for each OpenCL DEVICE, but other users I have talked to suggest disabling one CPU for each gpu CORE.  Of course, many cards like the GTX680 have 8 or more core per card.  I just want to make sure we are setting things correctly.

Thanks,
Mitch
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: Alexey Pasumansky on May 04, 2014, 10:16:08 AM
Hello Mitch,

One CPU should be disabled per one OpenCL Device. If hyperthreading is on we recommend to disable two threads.
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: Wishgranter on May 04, 2014, 11:41:48 AM
Hi MitchFX, on single CPU setup its advised to disable 1 core if HT then disable 2 cores per GPU, but we have observed on DualXeon setups that disabling all cores get us most of the OpenCL.........
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: mitchfx on May 04, 2014, 04:24:38 PM
Hello Mitch,

One CPU should be disabled per one OpenCL Device. If hyperthreading is on we recommend to disable two threads.

Alexey,

Thanks for the reply.  Just so I am perfectly clear if I have a single GTX680 card (8 cores) and an intel i920 cpu (4 physical cores / 8 with hyperthreading), I should disable TWO cpu cores?  Is this correct?

I want to make sure that when you say "per OpenCL device" you mean per CARD and not gpu core.

Thanks,
Mitch
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: mitchfx on May 04, 2014, 04:30:01 PM
Hi MitchFX, on single CPU setup its advised to disable 1 core if HT then disable 2 cores per GPU, but we have observed on DualXeon setups that disabling all cores get us most of the OpenCL.........

Hi Wishgranter,

Can you expand a little on your statement that "disabling ALL THE CORES gets the most out of OpenCL"?  Do you mean you simply disable all CPUs and use GPU processing only?  What kind of card are you using?

Thanks,
Mitch
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: Alexey Pasumansky on May 04, 2014, 05:05:30 PM
Quote
if I have a single GTX680 card (8 cores) and an intel i920 cpu (4 physical cores / 8 with hyperthreading), I should disable TWO cpu cores?  Is this correct?
Yes, that's correct. 6/8 CPU cores should be left active.
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: mitchfx on May 04, 2014, 08:15:03 PM
Quote
if I have a single GTX680 card (8 cores) and an intel i920 cpu (4 physical cores / 8 with hyperthreading), I should disable TWO cpu cores?  Is this correct?
Yes, that's correct. 6/8 CPU cores should be left active.

Thanks for the clarification Alexey!
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: Lambo on May 05, 2014, 11:43:37 PM
mitchfx, yes it seems they have found that if you are running multiple CPU's (Xeon for example) that disabling all the CPU's cores gives them the best performance.
Leo
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: mitchfx on May 06, 2014, 12:42:44 AM
mitchfx, yes it seems they have found that if you are running multiple CPU's (Xeon for example) that disabling all the CPU's cores gives them the best performance.
Leo

Hmmm, I'm going to try some tests.  I have dual xeons at work and single i7 at home (both with 680gtx cards) so pretty good for comparisons.
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: Mohabon on May 07, 2014, 10:44:31 AM
mitchfx, yes it seems they have found that if you are running multiple CPU's (Xeon for example) that disabling all the CPU's cores gives them the best performance.
Leo

Hello,

I have Dual Xeon (2x6=12 physical cores + 12 Cores HT), so total is 24 cores. I have also 2x ATI7970.

If i understand it right, Do you suggest o disable all 24 cores? I usually disable 4, so 20 are still enabled.

Thanks and regards,

M
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: Wishgranter on May 07, 2014, 12:46:52 PM
Hi Mohabon, can try our benchmark and report back what you get for results ?!? - enought on HIGH settings..... and let me know what CPU you have there.......
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: Mohabon on May 07, 2014, 01:01:21 PM
CPU are not so good: 2 x Intel Xeon E5-2620 Socket2011 15MB - 2.0Ghz

I have some other single CPU workstation that is way faster in aligning than this Dual Xeon because alignment requires CPU high-clock instead of multiple cores. But when building dense cloud or meshing, this Dual Xeon becomes more efficient and faster.

To conclude: you want me to disable 24 cores or only 4?

Thanks and regards
Title: Re: OpenCL Cores Enabled vs CPU Disabled?
Post by: Wishgranter on May 07, 2014, 01:20:28 PM
Disable all 24 cores..... and then disable 4..... when im running the test  and have all 32 cores disabled i see that CPU is up to 60 % used.....  they prepare-send data to the GPUs.....