ethomaz said:
You can't sum bandwidth dude... and 176GB/s is for GPU and CPU in PS4... they use the same memory controller... they share the bandwidth and memory... CPU uses approc. 20GB/s bandwidth... 90% of the PS4 bandwidth is for GPU.
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That link "example" has me puzzled ever since I saw it. Unfortunately it leads to people falsely "adding up numbers" like you correctly mention.
1. They couldn't figure out where the four dma controllers go so they put them idle at the bottom, without showing what they connect to. The display/Scan box should be drawn connected to the esram, of course, not placed in limbo (and the video encoder likely sits there, too).
2. Read command of the gpu is shown as 4G/s. But where are they reading from? Either from esram or from dram, so these bandwidth numbers are already allocated for at all times...
3. The gpu memory controller shows 0.5G/s write + 5.5G/s "read from dram". But where are they reading from? Either from esram or dram, so these bandwidth numbers are already allocated for at all times...
4. The gpu memory controller shows 102G/s r/w to esram and 42G/s r/w to dram. If that were true, there woud be two physically separated (256bit) data and (34bit) address busses, in addition to the physically separated 37G(s data/address bus to the gpu and another 25G/s data/address bus to the Northbridge. That is one hell of a bus layout. Congrats to the hardware engineers (or more likely, this diagram is nonsense).
All in all, this diagram is more puzzling than revealing..