Supermicro X11DDW-L/NT User Manual page 91

Chapter 4: UEFI BIOS
KTI Prefetch
If this feature is set to Enable, the KTI prefetcher will preload the L1 cache with data
deemed relevant to allow the memory read to start earlier on a DDR bus in an effort to
reduce latency. The options are Enable and Disable.
Local/Remote Threshold
This feature allows the user to set the threshold for the Interrupt Request (IRQ) signal, which
handles hardware interruptions. The options are Disable, Auto, Low, Medium, and High.
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 deadlines 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

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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