Interfaces
24
Datasheet
connector per channel. For dual-channel modes both channels must have an SO-DIMM
connector populated. For single-channel mode, only a single-channel can have an
SO-DIMM connector populated.
2.1.5
Technology Enhancements of Intel
®
Fast Memory Access
(Intel
®
FMA)
The following sections describe the Just-in-Time Scheduling, Command Overlap, and
Out-of-Order Scheduling Intel FMA technology enhancements.
2.1.5.1
Just-in-Time Command Scheduling
The memory controller has an advanced command scheduler where all pending
requests are examined simultaneously to determine the most efficient request to be
issued next. The most efficient request is picked from all pending requests and issued
to system memory Just-in-Time to make optimal use of Command Overlapping. Thus,
instead of having all memory access requests go individually through an arbitration
mechanism forcing requests to be executed one at a time, they can be started without
interfering with the current request allowing for concurrent issuing of requests. This
allows for optimized bandwidth and reduced latency while maintaining appropriate
command spacing to meet system memory protocol.
2.1.5.2
Command Overlap
Command Overlap allows the insertion of the DRAM commands between the Activate,
Precharge, and Read/Write commands normally used, as long as the inserted
commands do not affect the currently executing command. Multiple commands can be
issued in an overlapping manner, increasing the efficiency of system memory protocol.
2.1.5.3
Out-of-Order Scheduling
While leveraging the Just-in-Time Scheduling and Command Overlap enhancements,
the IMC continuously monitors pending requests to system memory for the best use of
bandwidth and reduction of latency. If there are multiple requests to the same open
page, these requests would be launched in a back to back manner to make optimum
use of the open memory page. This ability to reorder requests on the fly allows the IMC
to further reduce latency and increase bandwidth efficiency.
2.1.6
DRAM Clock Generation
Every supported SO-DIMM has two differential clock pairs. There are total of four clock
pairs driven directly by the processor to two SO-DIMMs.
2.1.7
System Memory Pre-Charge Power Down Support Details
The IMC supports and enables slow exit DDR3 DRAM Device pre-charge power down
DLL control. During a pre-charge power down, a slow exit is where the DRAM device
DLL is disabled after entering pre-charge power down for potential power savings.