Supermicro SuperStorage SSG-6049SP-DE1CR60 User Manual page 83

Chapter 6: UEFI BIOS
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
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) require-
ments. This feature is especially important for Virtualization Technology. The options are
Disable, Enable, and Auto.
Memory Configuration

Integrated Memory Controller (iMC)
Enforce POR
Select Enable to enforce POR restrictions on DDR4 frequency and voltage programming.
The options are POR and Disable.
PPR Type
Post Package Repair (PPR) is a new feature available for the DDR4 Technology. PPR
provides additional spare capacity within a DDR4 DRAM module that is used to replace
faulty cell areas detected during system boot. PPR offers two types of memory repairs.
Soft Post Package Repair (sPPR) provides a quick, temporary fix on a raw element in a
bank group of a DDR4 DRAM device, while hard Post Package Repair (hPPR) will take
a longer time to provide permanent repair on a raw element. The options are Auto, Hard
PPR, Soft PPR, and PPR Disabled.
83