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SuperStorage SSG-1129P-ACR10N4L User's Manual
IO Directory Cache (IODC)
Select Enable for the IODC (I/O Directory Cache) to generate snoops instead of gen-
erating 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
options 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
Select Enable to use "Sub NUMA Clustering" (SNC), which supports full SNC (2-cluster)
interleave and 1-way IMC interleave. Select Auto for 1-cluster or 2-cluster support de-
pending on the status of IMC (Integrated Memory Controller) Interleaving. The options
are
Disable
, Enable, and Auto.
XPT Prefetch
Select Enable for XPT (Extended Prediction Table) Prefetch support which will allow an
LLC request to be duplicated and sent to an appropriate memory controller based on the
recent LLC history to reduce latency. The options are
Disable
and Enable.
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 Disable and
Enable
.
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 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 Disable,
Enable
, and Auto.
