Forum

Author Topic: OpenCL Cores Enabled vs CPU Disabled?  (Read 7929 times)

mitchfx

  • Newbie
  • *
  • Posts: 31
    • View Profile
OpenCL Cores Enabled vs CPU Disabled?
« 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

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 10812
    • View Profile
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #1 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.
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Wishgranter

  • Hero Member
  • *****
  • Posts: 1202
    • View Profile
    • Museum of Historic Buildings
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #2 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.........
----------------
www.mhb.sk

mitchfx

  • Newbie
  • *
  • Posts: 31
    • View Profile
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #3 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
« Last Edit: May 04, 2014, 04:26:11 PM by mitchfx »

mitchfx

  • Newbie
  • *
  • Posts: 31
    • View Profile
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #4 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

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 10812
    • View Profile
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #5 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.
Best regards,
Alexey Pasumansky,
AgiSoft LLC

mitchfx

  • Newbie
  • *
  • Posts: 31
    • View Profile
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #6 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!

Lambo

  • Full Member
  • ***
  • Posts: 167
    • View Profile
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #7 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

mitchfx

  • Newbie
  • *
  • Posts: 31
    • View Profile
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #8 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.

Mohabon

  • Newbie
  • *
  • Posts: 48
    • View Profile
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #9 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

Wishgranter

  • Hero Member
  • *****
  • Posts: 1202
    • View Profile
    • Museum of Historic Buildings
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #10 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.......
----------------
www.mhb.sk

Mohabon

  • Newbie
  • *
  • Posts: 48
    • View Profile
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #11 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

Wishgranter

  • Hero Member
  • *****
  • Posts: 1202
    • View Profile
    • Museum of Historic Buildings
Re: OpenCL Cores Enabled vs CPU Disabled?
« Reply #12 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..... 
----------------
www.mhb.sk