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suson

Member

Registered: 2018-12-23

Posts: 24

Extra RAM usage when program run on dedicated GPU

My laptop has intel integrated graphics along with Nvidia Geforce GTX 950M with 4GB of VRAM. I am using nvidia prime offloading (the issue is same with the bumblee). I have one question, when I run a program with dedicated graphics I am seeing increased RAM usage.
When I run the android emulator with integrated graphics, the RAM usage is around 1,785MB. But when I run the same emulator with dedicated graphics using prime-run command, the VRAM usage is 500MB and RAM usage is around 2,186MB. I was expecting the RAM usage to decrease as the program is using VRAM instead of RAM. But as you can see the RAM usage increased instead of decreasing. The same thing happens with other programs like VLC.
I am not that expert in GPU stuff, it may be a normal thing. Can someone shed some light on me.
By the way, I am using the latest 5.8.1 Kernel and nvidia 450.57-90 drivers. Thank you in advance.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 23,287

Re: Extra RAM usage when program run on dedicated GPU

You can't just move everything in VRAM that is expected to be present in RAM and there will be an overhead because you are basically driving both the integrated and the dedicated graphics card plus whatever data structures are needed to provide the synchronisation between the two GPUs. As such I'd say somewhat of an increase can be expected  and normal here.

suson

Member

Registered: 2018-12-23

Posts: 24

Re: Extra RAM usage when program run on dedicated GPU

Thank you for clearing that out. Yeah you are right. But I was shocked to see the increased RAM to be nearly equal to the VRAM usage and thought I might have screwed something. I would test if same thing happens in windows or not and will inform you.