Patent ID: 7509463

Claim:
In processor system having two or more processors including a main memory, a power processor element (PPE) and a synergistic processor element (SPE) that operate on different sized memory access capabilities, a method for atomic operation, the method comprising: using the PPE to notify an SPE to perform a compare and swap operation on an address in main memory, wherein a size of the address is less than or equal to a maximum memory transfer size for the SPE and greater than a memory transfer size for the PPE, wherein the maximum memory transfer size for the SPE is larger than the maximum memory transfer size for the PPE; atomically performing the compare and swap operation with the SPE; and with the SPE, notifying the PPE of the success or failure of the compare and swap operation, wherein the compare and swap operation includes: performing a read-with-reservation of a stored value in the address with the SPE, performing a comparison with the SPE, wherein the comparison involves the stored value and one or more reference parameters, if the comparison is successful, performing a conditional write of a swap value to the address with the SPE.