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Does the "one CPU core free" affect AMD / OpenCL?
Posted: Wed May 11, 2016 1:30 am
by GPU timpster
I'd like to know if I should leave two CPU threads free for GPU folding along side CPU folding on AMD cards. I've read that F@H now uses only OpenCL, and am wondering if there are any such differences between the two.
Re: Does the "one CPU core free" affect AMD / OpenCL?
Posted: Wed May 11, 2016 5:41 am
by 7im
No need to make any changes to the client. OpenCL use started a (relatively) long time ago in computer time. That won't change unless the OEMs make significant driver model changes. And that is unlikely unless an operating system changes drastically.
Re: Does the "one CPU core free" affect AMD / OpenCL?
Posted: Wed May 11, 2016 3:25 pm
by bruce
AMD GPUs have always used OpenCL (well, at least since the very early days when they were ATI, beginning with HD 5xxx Series). NVidia will use eitehr OpenCL or their proprietary API called CUDA. It's to FAH's advantage to be able to use the same software on both brands of GPUs.
The need for 1 CPU for each GPU is created by driver design, not by FAH. Drivers are distributed by the hardware manufacturer and, as 7im has said, fundamental characteristics are unlikely to change.
Re: Does the "one CPU core free" affect AMD / OpenCL?
Posted: Fri May 13, 2016 1:46 pm
by toTOW
GPU timpster wrote:I'd like to know if I should leave two CPU threads free for GPU folding along side CPU folding on AMD cards.
Yes.
bruce wrote:The need for 1 CPU for each GPU is created by driver design, not by FAH. Drivers are distributed by the hardware manufacturer and, as 7im has said, fundamental characteristics are unlikely to change.
True, but for some (still unknown) reasons, some projects tends to requires two threads instead of only one ...
Re: Does the "one CPU core free" affect AMD / OpenCL?
Posted: Fri May 13, 2016 2:18 pm
by 7im
Sorry, that's not the general recommendation, toTOW.
But GPU Timpster is more than welcomed to try it for himself and see what works best for him. And appreciate any test test results you get. Run it for a week with one core free, then a week with two free, and note any difference in average PPD.
The other consideration here is if the CPU client loses more or less points than the GPU gains, if any.
Re: Does the "one CPU core free" affect AMD / OpenCL?
Posted: Fri May 13, 2016 6:32 pm
by bruce
Core_21 does a small amount of extra CPU processing every couple of frames, but the most you can save is maybe 1% of the TPF.
If you have a CPU that manages 8 threads, I'd leave two free because CPU folding with 7 threads is less than optimum ... 6 can be better. (or 12 threads, since 11 automatically uses 10).