Chapter 4: BIOS
99
Stale AtoS (A to S)
The in-memory directory has three states: I, A, and S states. The I (-invalid) state indicates
that the data is clean and does not exist in the cache of any other sockets. The A (-snoop All)
The S state (-Shared) indicates that the data is clean and may be shared in the caches
across one or more sockets. When the system is performing "read" on the memory and
if the directory line is in A state, we must snoop all other sockets because another socket
data. However, it may be the case that a line "reads" in an A state, and all the snoops come
back with a "miss". This can happen if another socket reads the line earlier and then has
silently dropped it from its cache without modifying it. If "Stale AtoS" is enabled, a line will
transition to the S state when the line in the A state returns only snoop misses. That way,
subsequent reads to the line will encounter it in the S state and will not have to snoop,
where there are many cross-socket reads. The options are Disable, Enable, and Auto.
LLC Dead Line Alloc
Enable,
Disable, and Auto.
Memory Conguration
To Next Page
Loading...
