Table of Contents
Advertisement
Link L0p Enable
Select Enable for the system BIOS to enable Link L0p support which will allow the CPU to reduce the UPI links from full
width to half width in the event when the CPU's workload is low in an attempt to save power. This feature is available for
the system that uses Intel processors with UPI technology support. The options are Disable, Enable, and Auto.
Note: You can change the performance settings for non-standard applications by us-
ing this parameter. It is recommended that the default settings be used for standard
applications.
Link L1 Enable
Select Enable for the BIOS to activate Link L1 support which will power down the UPI links to save power when the sys-
tem is idle. This feature is available for the system that uses Intel processors with UPI technology support. The options
are Disable, Enable, and Auto.
Note: Link L1 is an excellent feature for an idle system. L1 is used during Package
C-States when its latency is hidden by other components during a wakeup.
KTI Prefetch
Use this feature to configure the Prefetch setting supported by Keizer Technology Interconnect (KTI), also known as
Intel Ultra Path Interconnect (UPI) Technology. Select Enable for the KTI prefetcher to preload the L1 cache with data
deemed relevant, which will allow the memory read to start earlier on a DDR bus in an effort to reduce latency. Select
Auto for the KTI prefetcher to automatically preload the L1 cache with relevant data whenever is needed. The options
are Disable, Enable, and Auto.
IO Directory Cache (IODC)
Select Enable for the IODC to generate snoops instead of generating memory lockups for remote IIO (InvIToM) and/or
WCiLF (Cores). Select Auto for the IODC to generate snoops (instead of memory lockups) for WCiLF (Cores). The op-
tions are Disable, Auto, Enable for Remote InvItoM Hybrid Push, InvItoM AllocFlow, Enable for Remote InvItoM Hybrid
AllocNonAlloc, and Enable for Remote InvItoM and Remote WViLF.
SNC
Sub NUMA Clustering (SNC) is a feature that breaks up the Last Level Cache (LLC) into clusters based on the 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-clusters),
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 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 "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 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 Disable, Enable, and Auto.
107
Chapter 4: UEFI BIOS
Advertisement
Table of Contents
