A system and method improve caching efficiency in a data storage system by performing machine learning processes on metadata relating to extents of data blocks, rather than individual blocks themselves. Thus, once the storage devices are divided into extents, various metadata regarding access to the blocks within each extent are aggregated, and per-extent features are extracted. These features are used to train a data regression model that is subsequently used to infer a most likely “hotness” value for each extent at a future time. These predicted values, which may be further classified as e.g. “hot”, “warm”, and “cold” using thresholds, are used to implement the cache replacement policy. Embodiments scale to large and multi-layered caches, and may avoid common caching problems like thrashing, by adjusting the extent size. Policy goal functions may be optimized by dynamically adjusting the classification thresholds.

Method and apparatus for managing a front-end cache formed of ferroelectric memory element (FME) cells. Prior to storage of writeback data associated with a pending write command from a client device, an intelligent cache manager circuit forwards a first status value indicative that sufficient capacity is available in the front-end cache for the writeback data. Non-requested speculative readback data previously transferred to the front-end cache from the main NVM memory store may be jettisoned to accommodate the writeback data. A second status value may be supplied to the client device if insufficient capacity is available to store the writeback data in the front-end cache, and a different, non-FME based cache may be used in such case. Mode select inputs can be supplied by the client device specify a particular quality of service level for the front-end cache, enabling selection of suitable writeback and speculative readback data processing strategies.

Systems, apparatuses, and methods related to hierarchical memory are described. A hierarchical memory system that can leverage persistent memory to store data that is generally stored in a non-persistent memory. Logic circuitry can be configured to determine that a request to access a persistent memory device corresponds to an operation to divert data from the non-persistent memory device to the persistent memory device, generate an interrupt signal, and cause the interrupt signal to be asserted on a host coupleable to the logic circuitry as part of the operation to divert data from the non-persistent memory device to the persistent memory device. Access data and control messages can be transferred between or within a memory device, including to or from a multiplexer and/or a state machine. A state machine can include logic circuitry configured to transfer interrupt request messages to and receive interrupt request messages.

Methods, systems, and devices for prefetch signaling in a memory system or sub-system are described. A memory device (e.g., a local memory controller of memory device) of a main memory may transmit a prefetch indicator indicating a size of prefetch data associated with a first set of data requested by an interface controller. The size of the prefetch data may be equal to or different than the size of the first set of data. The main memory may, in some examples, store the size of prefetch data along with the first set of data. The memory device may transmit the prefetch indicator (e.g., an indicator signal) to the interface controller using a pin compatible with an industry standard or specification and/or a separate pin configured for transmitting command or control information. The memory device may transmit the prefetch indicator while the first set of data is being transmitted.

A computing system can include an off-chip memory and processing unit integrated circuitry. The processing unit IC can include on-chip compute circuitry, a first on-chip memory and a second on-chip memory. The off-chip memory can be configured to store instructions and data The first on-chip memory can be configured to store reusable portions of the instructions and or data for use by the on-chip compute circuitry. The second on-chip memory configured to cache portions of instruction and data for current use by the on-chip compute circuitry.

A storage server and a method of driving the storage server are provided. The storage server includes a processor configured to: generate a plurality of flush write commands based on a write command of first data provided from a host, provide a replication command corresponding to the write command to an external storage server, and receive an operation completion signal of the replication command from the external storage server; a memory storing a program of a log file to which the plurality of flush write commands are logged; and a storage device configured to receive a multi-offset write command including one or more flush write commands logged to the log file, and perform a flush operation on the multi-offset write command. The processor is further configured to provide the multi-offset write command to the storage device based on the log file after receiving the operation completion signal.

A semiconductor device includes: a first cache that includes a first memory and rewrite flags that indicate whether rewriting has been performed for each piece of data held in the first memory; and a second cache that includes a second memory and a third memory that has a lower writing speed than the second memory, stores data evicted from the first cache in the second memory when a rewrite flag corresponding to the evicted data indicates a rewrite state, and stores data evicted from the first cache in the third memory when a rewrite flag corresponding to the evicted data indicates a non-rewrite state.

A data storage system provides persistent storage in bulk non-volatile memory. A controller of the data storage system receives a host write command and buffers associated host write data in both a first write cache in non-volatile memory and a mirrored second write cache in volatile memory. The controller destages the host write data to the bulk non-volatile memory from the second write cache but not the first write cache. The controller services relocation write commands requesting data relocation within the bulk non-volatile memory by reference to the second write cache. Servicing the relocation write commands includes buffering relocation write data in the second write cache but not the first write cache and destaging the relocation write data to the bulk non-volatile memory from the second write cache.

A method for constructing a persistent memory index in a non-uniform memory access architecture includes: maintaining partial persistent views in a persistent memory and maintaining a global volatile view in a DRAM; an underlying persistent memory index processing a request in a foreground thread when cold data is accessed; when hot data is accessed, reading a key-value pair for a piece of hot data in the global volatile view in response to a query operation carried in the request, and in response to an insert/update/delete operation carried in the request, updating a local partial persistent view and the global volatile view; and in response to a hotspot migration, a background thread generating new partial persistent views and a new global volatile view, and recycling the partial persistent views and the global volatile view for old hot data into the underlying persistent memory index.

Disclosed herein are a hybrid memory management apparatus and method for an many-to-one virtualization environment. The hybrid memory management apparatus is implemented in an inverse-virtualization-based multi-node computing system including multiple physical nodes, each containing hybrid memory in which DRAM and NVRAM coexist, a virtual machine, and hypervisors, and includes memory for storing at least one program, and a processor for executing the program, wherein the program includes a remote request service module for processing a page-related request with reference to the hybrid memory and responding to the page-related request by transmitting a result of processing, an internal request service module for processing an internal page fault request with reference to a hybrid memory and responding to the internal page fault request, and a data arrangement module for responding to an inquiry request for a location at which a newly added page is to be arranged in the hybrid memory.