GTX 1660Ti Compute Performance

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Re: GTX 1660Ti Compute Performance

Postby bruce » Tue Mar 12, 2019 4:29 pm

jjbduke2004 wrote:I do notice that the graphics core is taking up about 30% CPU which I imagine means that one of the four processor cores is fully occupied with another running a second, less demanding thread. Video bus usage (PCIe 3.0) was around 43% so I wonder if my processor is the bottleneck in feeding the data since the past few work units only occupied 87-93% of the video card.

Most people don't notice, but I've observed that the CPU supporting a GPU behaves in at least 3 different ways, and it can change at different times during the processing of a WU.
1) The CPU is transferring data to/from main RAM and the GPU's VRAM.
1a) this may use 100% of one CPU thread or
1b) This may use less than 100% of one CPU thread ... depending on the particular driver you are running.
2) Periodically, FAHCore_nn runs a "sanity check" validating the current WU's status by comparing certain calculations done by the GPU with similar calculations done by the CPU. This is typically done when a checkpoint is written. This may use one or more additional CPU threads until that comparison is completed. It rarely lasts very long so it probably doesn't slow up the overall performance of that WU enough to notice.

Both 30% and 43% are reasonable numbers, depending on how many CPU threads your CPU has and on the exact state of the calculations.
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Re: GTX 1660Ti Compute Performance

Postby toTOW » Tue Mar 12, 2019 6:34 pm

jjbduke2004 wrote:Update 4: I think something happened midway through that caused the card to stop "Boosting" and run at stock 1500 MHz despite wiggle room in heat dissipation and power consumption.

This usually happens after a driver recovery ... do you have something like this in Event viewer ?
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Re: GTX 1660Ti Compute Performance

Postby MeeLee » Tue Mar 12, 2019 8:02 pm

jjbduke2004 wrote: it seems to do it's own thing, which I've learned is "normal" for NVIDIA Boost 3.0/4.0).

A card usually has a boost speed, at which it runs higher frequencies, to the point where the sink's temperature hits a certain temperature (usually ~60-65C).
After that, it'll hit stock speeds. You can still increase GPU speed after that, to the second barrier, which is the voltage limitation.
Once you increase the voltage, you can run higher speeds to the point where the card hits the thermal limit, and starts thermal throttling.
Unless you can equip it with a better cooling system, hitting the thermal limit usually means you're running it as high as it allows you to.

jjbduke2004 wrote:I do notice that the graphics core is taking up about 30% CPU which I imagine means that one of the four processor cores is fully occupied with another running a second, less demanding thread. Video bus usage (PCIe 3.0) was around 43% so I wonder if my processor is the bottleneck in feeding the data since the past few work units only occupied 87-93% of the video card.


If your card is an nVidia card, it will always show 1 CPU thread fully occupied under light or heavy use.
Any modern CPU will not bottleneck your card.
I believe it takes a ~4-6 year old Atom processor (or slower), to bottleneck a 1660 for folding.
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Re: GTX 1660Ti Compute Performance

Postby jjbduke2004 » Wed Mar 13, 2019 2:20 pm

toTOW wrote:This usually happens after a driver recovery ... do you have something like this in Event viewer ?

Nothing in the logs, but this sounds plausible. I do see some sort of FAH crash/resource overuse. I may have had a lock up and reset the machine, I probably had a VirtualBox Linux session (not for folding) running at the same time. I can't remember. I do know that there was a drop of in PPD the next few days afterwards and it also coincides with an episode where I had 5 "bad" work units in rapid succession.

The 9AM CDT stats update shows 699,434 PPD in the last 24 hours. I have added a little bit of CPU folding on 3 cores but that adds ~12k PPD.

MeeLee wrote:If your card is an nVidia card, it will always show 1 CPU thread fully occupied under light or heavy use.

Sounds like the process has a continuous while loop that doesn't wait, pend, block, or yield so it's allowed to hit 100% on the core.
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Re: GTX 1660Ti Compute Performance

Postby Joe_H » Wed Mar 13, 2019 2:53 pm

jjbduke2004 wrote:Sounds like the process has a continuous while loop that doesn't wait, pend, block, or yield so it's allowed to hit 100% on the core.

From others investigating this in the past, that is how nVidia has implemented its OpenCL support in the driver. It can b e interrupted by a higher priority process, and in some cases shared with a process thread for another nVidia GPU. But one CPU thread will be always active and show 100% usage. Some have characterized as being a "spin wait".
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