Supermicro X13SRA-TF - Page 91

Chapter 4: UEFI BIOS
91
Chipset Conguration
Warning: Setting the wrong values in the following features may cause the system to malfunc-
tion.
North Bridge
This feature allows you to congure the following North Bridge settings.
Uncore Conguration
The following information is displayed.
• Number of CPU
• Global MMIO Low Base / Limit
• Global MMIO High Base / Limit
• Pci-e Conguration Base / Size
SNC
Sub NUMA Clustering (SNC) is a feature that breaks up the Last Level Cache (LLC) into
clusters based on address range. Each cluster is connected to a subset of the memory
controller. Enable this feature to improve average latency and reduce memory access
congestion for higher performance. The options are Auto, Disable, Enable SNC2 (2-clus-
ters), and Enable SNC4 (4-clusters).
Stale AtoS (A to S)
The in-memory directory has three states: I, A, and S states. The I (-invalid) state indi-
cates 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
modied 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 modied state. If this is the case, a "snoop" will
return the modied 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, saving the latency and snoop bandwidth. Stale "AtoS" may
be benecial in a workload where there are many cross-socket reads. The options are
Disable, Enable, and Auto.