The preferences of BOINC manager (version 6.4.5) has an option, "On multiprocessor systems, use at most % of the processors." However, this preference has no apparent effect on the number of GPU's that are used, as it seems to only affect the number of CPU's used.

How can this application be configured to use only one particular GPU without rudely seizing _all_ the GPU's available in the system for itself?

As of now that's not possible.

Maybe someone of the BOINC devs will hear you and eventually understand that GPU resources should be treated different than CPUs if you also post this question as a feature request to the BOINC forum...
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As of now that's not possible.

Maybe someone of the BOINC devs will hear you and eventually understand that GPU resources should be treated different than CPUs if you also post this question as a feature request to the BOINC forum...

Your 'Restricting use to one GPU....' question caught my attention. But, your reason (or lack a reason) for wanting to 'select' or 'single out' 1 GPU out of many is missing.

How can this application be configured to use only one particular GPU without rudely seizing _all_ the GPU's available in the system for itself?

It also depends on the game ...

I used to run EverQuest on three different systems with varying capabilities and I never noticed a problem ... of course that was then and this is now with a significantly different BOINC Manager ... so, my experience may be out of date ...

Though I have run Spore and did not notice any problems...

I suppose if you are playing a high frame rate game (first person shooter I suppose) this may be an issue ... or an urban legend ... :)

Anyway, I do know that many always did shut down BOINC and several would complain days later that they forgot to start it up again when they quit playing ... but that is a different issue ...

I have not tired games with BOINC running a CUDA task yet though ... too many other things on my limited mind ...

Nevermind the BOINC cpu load during games, the problem is much more severe when crunching CUDA. But it gets less pronounced the faster the card is.

MrS

This advantages of restricting BOINC to use just one GPU applies not only to gaming.
Think about recent motherboards based on CUDA capable nvidia IGP chipsets.
Those might have 16 shader units at a low clock speed. But as BOINC itself doesn't care about this, it will start a WU on the IGP that will fail to meet the deadline.

Actually, I thought about buying a new nvidia based µATX board with an integrated Geforce 9300 or 9400. That would be enough to power my Linux desktop with enabled composite effects. Right now this is still handled by my 8800GTs and often enough its kind of choppy :-/ I dropped the idea got now...

Your 'Restricting use to one GPU....' question caught my attention. But, your reason (or lack a reason) for wanting to 'select' or 'single out' 1 GPU out of many is missing.

Thus, restricting usage to certain GPU devices is desirable.

If the BOINC application interface provides no help, is there another way to limit GPU usage via another layer of GPUGRID?

Apparently, no user friendly method exists to tell BOINC to stay off particular GPUs, aside from shutting the whole process down.

Since GPUGRID assigns one process per GPU, manually suspending a process remains an option. The drawback to this workaround is that the associated work unit becomes frozen.

Regarding the integrated GPU, disabling it entirely remains an alternative to manually freezing the associated GPU process every single time BOINC is started. Yet disabling the integrated GPU denies an otherwise available GPU to other applications (such as high definition video), thus reducing overall system performance at full load.

Meanwhile, none of these workarounds or annoying trade-offs need be considered for applications that offer a method of excluding specific GPU devices.

Apparently, no user friendly method exists to tell BOINC to stay off particular GPUs, aside from shutting the whole process down.

Since GPUGRID assigns one process per GPU, manually suspending a process remains an option. The drawback to this workaround is that the associated work unit becomes frozen.

Regarding the integrated GPU, disabling it entirely remains an alternative to manually freezing the associated GPU process every single time BOINC is started. Yet disabling the integrated GPU denies an otherwise available GPU to other applications (such as high definition video), thus reducing overall system performance at full load.

Meanwhile, none of these workarounds or annoying trade-offs need be considered for applications that offer a method of excluding specific GPU devices.

From my point of view the problems which the BOINC team has tried to adress in the last months (with limited success) seem almost trivial compared to this.. so I wouldn't hold my breath for a quick solution either.

MrS