Question about multithreading in hardware mode

[Serial Hacker]

sure new API allow to teleport the data directly without passing by the pcie link. It is much faster

I Hope Gabest share the same point of view as you do as he seem to be pretty serious about supporting Intel's new instructions every year or so and i heard the amount of effort required is not that big when it comes to gaming, not sure about emulation

Vulkan seems a bit distant future tbh

[sirdaniel]

Hi all.
Some sort of avoiding transfers between CPU<>GPU was creating an APU, which has same physical memory for CPU and GPU. BUt thats not all, because CPU cant normally grab data that is assigned to GPU. To help that, they created a zero_copy in OpenCL API. So a small OpenCL program can be written with zero copy so the data can be copied from GPU to CPU pool just instantly in memory. The effect would be like no copy at all or instant copy (with the speed of RAM). This is somehow "software" solution. The "hardware" one is in Carrizo which should be compatible with HSA 1 and that would be accessing the same data in memory directly by GPU or CPU.
I dont know if such big project like pcsx2/gsdx can be programmed that way, but there is actually an Opencl version. I am just a user, like read technical stuff, but dont know programming. Any dev can look on datasheets and try this? Unfortunately, AMD's hype got lowered on this matter. So, maybe that small chip Carrizo will make progress on speed?

[gregory]

Yes we know about it and GSdx already has been ported to openCL but it was never tested on APU (I don't think the port uses zero copy anyway).

APU win in memory transfer but loose on GPU/CPU side. In my opinion to really exploit APU, GSdx will need a dedicated texture cache/vertex buffer with zero copy feature. However all PCSX2's dev have a dedicated GPU so it won't be for today.

[Akio]

So the reason why SW mode is slow is because of the heavily lower Bandwidth ? interesting...

No, the reason is the CPU is used for rendering.

Anyway, I don't understand the talk about PCIe. The bandwidth of the system RAM is lower than that of PCIe, so PCIe can't be the bottleneck.

[Serial Hacker]

No, the reason is the CPU is used for rendering.

that doesn't make any sense just because i use my left hand rather than my right hand shouldn't make everything tad slower

[Akio]

that doesn't make any sense just because i use my left hand rather than my right hand shouldn't make everything tad slower

It's more like using your left foot instead of your right hand to write.

[Serial Hacker]

It's more like using your left foot instead of your right hand to write.

The PS2 Graphic Synthesizer is not as close to the modern day GPUs as you make it sound

[ssakash]

on software mode, only a rendering of a texture quad is done. CPU is the important factor influencing speed on software mode.

[Akio]

The PS2 Graphic Synthesizer is not as close to the modern day GPUs as you make it sound

You can prove it by setting the extra rendering threads to 3 in case your CPU has 4 cores, then run a game and look at the CPU usage. If the system RAM or another component is the bottleneck, the CPU usage should be lower than 50% because the CPU has to wait. Then again, the extra rendering threads would be kind of pointless if the CPU wasn't the bottleneck.

[paraemuladores]

No, the reason is the CPU is used for rendering.

1) Is this the reason why increasing the internal resolution makes the game slower?
2) If so, is there anyway to make the emulator use the GPU for rendering? Because my GPU is a reasonably good one (Nvidia GeForce N560GTX), and I believe that would increase the game's speed.