current state of GPU affinity?

Hardware
21

Hey yall

I am setting up a dual K6000 affinity system. The last time I used affinity using the -gpu X .bat file commands, when I dragged a window from the instance on one card to a monitor on the other card, it would stop rendering.

Currently it is still rendering, is this a new “feature”. I read in the wiki that you want to avoid bring the windows from one gpu onto the other, so does this mean the drivers automatically start sharing data now when it thinks you want the instance on the other card?

Is there a better way now to test if affinity is truly working? Looking at GPU-Z when I keep the two instances on the seperate sets of monitors per card I can definitely see one driving harder than another when I look at a heavier render, but what is curious is that the card I am not messing with seems to dip in usage when the other goes up, and then they both even back to the same percentage when I put the one instance back to perform mode doing the exact same operation as the other.

Main questions are:

  1. has affinity changed so that even if you bind an instance to a single card, it will work on the other if asked to?

  2. when launching in designer mode and then using a start script to set the perform window to a monitor on the appropriate care before going to perform mode, does this put a flaw in my affinity usage since the file started in designer mode on the non-bound card?

  3. is there any further setup needed in 3d settings to achieve affinity now (like disabling mosiac, or enabling?), or is using the cmd line “-gpu X” enough?

Muchas gracias!

P

22

If you drag a window that has been rendered on one GPU to a monitor connected to a different GPU, the OS will copy the buffer across to be displayed on the other GPU. This is a feature of the newer drivers/Windows 7 since GPU affinity came out (back in XP days). There is a performance penalty, but it ‘works’. As far as I know there isn’t a penalty if you window starts on the wrong GPU but it later moved onto the correct GPU.

In the newer experimental there is more information about monitors and which ones are part of the process’ affinity, in the Monitors DAT and the monitors python object.

You shouldn’t need to do anything other than use -gpu as before

23

Awesome, thank you malcolm!