Panajev2001a said:
Gubbi, when talking about coherency what do you make of this Hofstee Quote in his HPCA 2005 article
Local Store addresses do have an alias in the Power
processor address map and transfers to and from Local
Store to memory at large (including other local stores) are
coherent in the system. As a result a pointer to a data
structure that has been created on the Power processor can
be passed to an SPE and the SPE can use this pointer to
issue a DMA command to bring the data structure into its
local store in order to perform operations on it. If after
operating on this data structure the SPE (or Power core)
issues a DMA command to place it back in non-LS
memory, the transfer is again coherent in the system
according to the normal Power memory ordering rules.
?
This just says main memory is coherent with respect to reads and writes from SPU and the PPU(you'd be in big trouble if it wasn't
) . It doesn't say that two LSes will be coherent with respect to each other if both were read from the same piece of main memory.
