GPU Memory going down

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Mohammad Abouali
Mohammad Abouali 2014-10-15
评论： Adam 2014-10-20
Hi,
I have a Mac Book Pro with NVIDIA GeForce GT 750M 2048 MB installed.
I noticed that when I am trying to assign a variable using GPUARRAY, I go out of GPU memory when I shouldn't.
So, check the online docs and I was instructed to reset the device. I did but no luck. However, I got something even more confusing. It seems that by reseting my GPU device actually the memory goes down instead of going up. Here it is:
>> format longg
>> d=gpuDevice;d.AvailableMemory/1024/1024
ans =
807.6171875
>> reset(d); d.AvailableMemory/1024/1024
ans =
659.1171875
>> reset(d); d.AvailableMemory/1024/1024
ans =
555.4921875
>> reset(d); d.AvailableMemory/1024/1024
ans =
633.1171875
>> reset(d); d.AvailableMemory/1024/1024
ans =
615.1171875
>> reset(d); d.AvailableMemory/1024/1024
ans =
633.1171875
>> reset(d); d.AvailableMemory/1024/1024
ans =
581.1171875
By the way, note that for the first line after "format longg", I just restarted my entire system, and just launched the MATLAB and then issue that commands. So nothing else was even running on my system. Yet only about 800MB of the total 2000MB gpumemory was available within MATLAB.
Any Idea what is going on?
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Matt J
Matt J 2014-10-20
Do you have a single graphics card, or multiple?
Adam
Adam 2014-10-20
Just one so that could certainly be a factor I guess. Though it does also mean that card is absolutely used for everything else the system may be doing related to graphics.

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回答（1 个）

Matt J
Matt J 2014-10-17
But that aside as I said, I was not running anything on the machine. and If I just type that over and over this happens.
The display functions of your monitor are always running, though, and at least one of your graphics cards is always servicing that. In Windows, there are settings to designate one card as the display handler. Presumably, there is a way to do likewise on a Mac. If you can verify that the card you are using for GPGPU is not tied to the display, it would be informative.
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Matt J
Matt J 2014-10-17
编辑：Matt J 2014-10-17
Why not? "Available Memory" surely refers to the memory on the card that the display is not using, and surely only that memory is controlled by reset(). Further, the mere act of typing "reset(d)" causes the display to change its status. I would also point out that your memory numbers aren't going down all the time. They seem to fluctuate up and down randomly.
Yes, it's still a theory, but it's worth eliminating as a consideration, if nothing else.
Matt J
Matt J 2014-10-17
编辑：Matt J 2014-10-17
that's about 200MB reduction in memory after multiple time reseting the device, without putting any new request to the device.
I don't say it makes sense that the memory fluctuations are that large, or that it's a mark of good software engineering. I'm just saying that when you lose memory, it must go somewhere, and maybe the display is taking it. It's as good an initial suspect as any if it's the only other known thing using the card.

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