Routing of memory transactions
An apparatus for processing data is provided comprising persistent memory circuitry, non-persistent memory circuitry and memory controller circuitry. The memory controller circuitry provides two or more memory sub-channels and each memory sub-channel is for routing of memory access transactions for at least one of the persistent memory circuitry and the non-persistent memory circuitry. The memory controller circuitry has channel selection circuitry to detect when there are no non-persistent memory transactions on one of the two or more memory sub-channels and responsive to the detection, is to route any persistent memory transactions to a different one of the two or more memory sub-channels. A memory controller apparatus, a persistent memory Dual In-line Memory Module, a method and computer program are also provided.
1 . An apparatus for processing data comprising:
persistent memory circuitry;
non-persistent memory circuitry; and
memory controller circuitry to provide two or more memory sub-channels, each memory sub-channel for routing of memory access transactions for at least one of the persistent memory circuitry and the non-persistent memory circuitry;
wherein the memory controller circuitry comprises channel selection circuitry to detect when there are no non-persistent memory transactions on one of the two or more memory sub- channels and responsive to the detection, to route any persistent memory transactions to a different one of the two or more memory sub-channels, wherein the channel selection circuitry preferentially directs persistent memory transactions to a sub-channel that has active non- persistent memory traffic.
2 . The apparatus of claim 1 , comprising power management circuitry to transition the one memory sub-channel from a higher power mode to a lower power mode responsive to detection of there being no non-persistent memory transactions on the sub-channel.
3 . The apparatus of claim 2 , wherein at least one of the non-persistent memory circuitry and the persistent memory circuitry comprises a Dual Inline Memory Module, DIMM.
4 . The apparatus of claim 3 , wherein the non-persistent memory circuitry is a DIMM comprising a plurality of Double Data Rate, DDR, memory devices.
5 . The apparatus of claim 4 , wherein the DIMM comprises DDR Input/Output circuitry and wherein the transitioning of the one memory sub-channel to the lower power mode further comprises sending a control signal to turn off a clock to the DDR Input/Output circuitry.
6 . The apparatus of claim 3 , wherein the one memory sub-channel on which there are no non-persistent memory transactions is a DDR sub-channel and wherein the transitioning of the DDR sub-channel to the lower power mode comprises the memory controller circuitry issuing a self-refresh command to the DDR sub-channel.
7 . The apparatus of claim 3 , wherein the DDR memory devices of the DIMM comply with the Joint Electron Device Engineering Council, JDEC, DDR5 memory specification or later.
8 . The apparatus of claim 1 , wherein the memory controller circuitry comprises a global memory controller component to control both the persistent memory transactions and the non-persistent memory transactions and comprises a local memory controller component dedicated to controlling the persistent memory transactions.
9 . The apparatus of claim 8 , wherein the local memory controller component is to route any persistent memory transactions upstream to the global memory controller and wherein the global memory controller is to allocate one of the two or more memory sub-channels for routing of the persistent memory transactions.
10 . The apparatus of claim 9 , wherein the global memory controller comprises a persistent memory scheduler to schedule persistent memory transactions and at least one non-persistent memory scheduler to schedule non-persistent memory transactions.
11 . The apparatus of claim 10 , wherein the global memory controller component is either a part of the persistent memory scheduler or cooperates with the persistent memory scheduler to route the persistent memory transactions to one of the two or more memory sub-channels.
12 . The apparatus of claim 1 , comprising processing circuitry to issue one or more memory transactions for the persistent memory circuitry or the non-persistent memory circuitry.
13 . A dual inline memory module, DIMM, comprising:
two or more persistent memory devices;
local memory controller circuitry to control processing of persistent memory transactions corresponding to one or more of the persistent memory devices using two or more memory sub-channels, the two or more memory sub-channels to be shared with transactions of a non-persistent memory DIMM;
channel selection circuitry to redirect any currently pending persistent memory access transactions corresponding to one of the two or more memory sub-channels for which there are currently no active persistent memory transactions, wherein the redirection is to divert any pending transactions away from the one memory sub-channel to a different memory sub-channel, and wherein the channel selection circuitry preferentially directs persistent memory transactions to a sub-channel that has active non-persistent memory traffic.
14 . The DIMM of claim 13 , wherein the pending memory transactions of the one memory sub-channel are redirected upstream to global memory controller circuitry having scheduling circuitry for both the persistent memory DIMM and the non-persistent memory DIMM.
15 . Global memory controller circuitry comprising:
first scheduling circuitry to schedule memory transactions corresponding to non- persistent memory transactions;
second scheduling circuitry to schedule memory transactions corresponding to non- persistent memory transactions; and
channel selection logic to select from two or more sub-channels, at least one sub-channel for servicing persistent memory transactions, the selection to avoid a sub-channel currently in a self-refresh mode of operation for processing the persistent memory transactions, wherein the channel selection logic preferentially selects a sub-channel that has active non-persistent memory traffic for servicing persistent memory transactions.
16 . The global memory controller circuitry of claim 15 , wherein at least one of the non-persistent memory transactions and the persistent memory transactions are DIMM transactions.
17 . The global memory controller circuitry of claim 15 , wherein the persistent memory transactions are to be performed by a persistent memory DIMM and wherein the channel selection logic is to put the persistent memory DIMM in a single sub-channel mode to avoid the sub-channel currently in the self-refresh mode of operation with respect to the non- persistent memory.
18 . The global memory controller circuitry of claim 15 , wherein the channel selection logic is to detect an absence of non-persistent memory transactions on a first sub-channel of the two or more sub-channels and, responsive to the detection, route the persistent memory transactions to a different one of the two or more memory sub-channels for servicing.
19 . The global memory controller circuitry of claim 18 , wherein, in response to there being no non-persistent memory transactions on first sub-channel, the channel selection logic is to issue a self-refresh command to the first sub-channel to perform self-refresh.
20 . The global memory controller circuitry of claim 15 , further comprising power control circuitry to transition the first sub-channel from a higher power mode to a lower power mode responsive to detection of there being no non-persistent memory transactions on the first sub-channel.