Supermicro X11DPG-HGX2 User Manual page 81

Chapter 4: UEFI BIOS
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) state indicates that the data may exist in another socket in an exclusive or modified
state. 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 may have the line in a modified state. If this is the case, a "snoop" will return the
modified 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 the "Stale AtoS"
feature 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, saving the latency and snoop bandwidth. Stale "AtoS" may be
beneficial in a workload where there are many cross-socket reads. The options are Disable,
Enable, and Auto.
LLC Dead Line Alloc
Select Enable to opportunistically fill the dead lines in the LLC. The options are Enable,
Disable, and Auto.
Isoc Mode
Select Enable to enable Isochronous support to meet QoS (Quality of Service) requirements.
This feature is especially important for Virtualization Technology. The options are Disable,
Enable, and Auto.
Memory Configuration

Enhanced PPR(Post Package Repair)
Select Enable to enable DRAM test and Enhanced PPR function. The options are Disable
and Enable.
Enforce POR (Plan of Record)
Select POR to enforce POR restrictions for DDR4 memory frequency and voltage
programming. The options are POR and Disable.
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