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Yet, the floating point operations ON THE CPU are what many games use, e.g. on PC games.
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The 2700g (in contrary to desktop GPUs) accepts fixed point data as input and converts them to floating point for further processing. It is mainly designed to work with a CPU without fp unit. T&L has to be done on the PXA270 though, using fixed point arithmetics (ie. WMMX).
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The PXA270 has fast local SRAM too, just far less of it (this mem is also used for LCD frame buffers in non-accelerated PDAs and phones). It's somewhat irrelevant how long it takes for the data to get into local memory.
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You compare apples with oranges here. The eDRAM in the PSP is exclusively used as screenbuffer, z-buffer and texture buffer. Its is very comparable to the memory exclusively used by the 2700G and not the memory the PXA270 has access to.
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Stated another way, imagine that all of the data a CPU needs to use to render the next scene (or play the next level etc.) fits into the local 2-8 megabytes of eDRAM. I bet this is the case for most games on the PSP. It can spend a comparatively long time loading this data into eDRAM, but then it has everything locally and can perform compute-intensive tasks FAR better than the PXA270 could, because the PXA270 is ALWAYS limited by its external memory access times.
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See above.
Now before you argue, that the eDRAM is still faster, you need to keep in mind, that the 2700G is a tile based (deferred) renderer, which is much more bandwidth efficient than traditional 3d hardware.
I also assume, that the PSP is plaqued by the same poor design choices made with the PS2. Out of the 2MB VRAM less than 1MB can be used for (uncompressed) textures, which makes constant swapping /streaming necessary. There is possibly no multi texturing support either (like PS2)
It seems to me, that similar to the PS2, the PSP is a brute force approach, where the pure numbers suggest a much better real live performance than it really has.
Still while looking at the numbers, the PSP seems to be about half as fast as the PS2 regarding fillrate and polygon throughput. The 2700G is comparable to a DC, possibly little slower.
Tala