philiptaylor
Host CPU accesses: HOST_COHERENT explanation
Hello!
First of all, thank you very much for the time you invested in this article! I'm trying to understand concept of system memory visible to GPU and write-combined memory. I read papers regarding the topic and still can't get full image in my mind.
What you wrote there: "Writes are cached a little bit - bytes written to the same cache line are collected in a write buffer, and eventually the write buffer will be flushed to VRAM in a single memory transaction."
What concerns me: write combined memory is system memory(located in RAM, not VRAM) as far as I got it right. Then, assume CPU writes to region of write-combined memory(RAM) and then GPU will access that memory through PCIe and put it in it's caches eventually. This doesn't look like CPU will write anything to VRAM in here.
I might got something wrong or just didn't understand the concept of write-combined memory correct. If you can explain this a bit, it would be very great.
