Ensuring data security when tiering volatile and non-volatile byte-addressable memory. A portion of cache data stored in a first memory that is byte-addressable and volatile is identified for copying to a second memory that is byte-addressable and non-volatile. The portion of cache data is associated with cryptographic requirements for storing the portion of cache data on non-volatile storage. Cryptographic capabilities of the second memory are identified. When each of the cryptographic requirements is met by the cryptographic capabilities, the portion of cache data is copied to the second memory while relying on the second memory to encrypt the portion of cache data. When at least one cryptographic requirement is not met by the cryptographic capabilities, the portion of cache data is encrypted to generate an encrypted portion of cache data, and the encrypted portion of cache data is copied to the second memory.

A method for retaining data pages in a cache is disclosed. In one embodiment, such a method stores multiple data pages in a cache. The method calculates, for each data page, a cost associated with promoting the data page from persistent storage media to the cache. The cost takes into account any data transformations (decryption, decompression, etc.) that are needed to promote the data page from the persistent storage media to the cache. In certain embodiments, the cost is represented as a score that is assigned to each data page. The method retains each data page in the cache for an amount of time that is related to its cost, such that data pages with a higher cost are retained in the cache longer than data pages with a lower cost. A corresponding apparatus and computer program product are also disclosed.

Embodiments of the present invention disclosure relate to a memory system, a memory controller, and an operating method. With regard to a function group including all or some functions included in one of multiple binary codes stored in the memory device, a binary code including a first function that is executed at a first timepoint is loaded into a first memory area at a second timepoint that precedes the first time point, thereby minimizing the operation delay time of the memory system, and minimizing the overhead occurring in the processing of calling a specific function.

A cuckoo cache has plural buckets of plural cells each. The cells within a bucket are ranked to approximate relative usage recency. New items can be inserted into empty cells; when a bucket is full, room for a new item can be made by laterally transferring an older item to an alternative bucket. When empty cells and lateral transfers are unavailable, an item is selected for eviction based on the usage recency rank of the containing cell. When a match is found, depending on the embodiment, the hit item can be promoted within its bucket, to its alternative bucket, or to a separate tier of the cuckoo cache. The items can be key-value pairs. No metadata is required to track usage recency so that the cuckoo cache can be a very space efficient tool for finding cached values by their keys.

Various embodiments are provided for providing byte granularity accessibility of memory in a unified memory-storage hierarchy in a computing system by a processor. A location of one or more secondary memory medium pages in a secondary memory medium may be mapped into an address space of a primary memory medium to extend a memory-storage hierarchy of the secondary memory medium. The one or more secondary memory medium pages may be promoted from the secondary memory medium to the primary memory medium. The primary memory medium functions as a cache to provide byte level accessibility to the one or more primary memory medium pages. A memory request for the secondary memory medium page may be redirected using a promotion look-aside buffer (PLB) in a host bridge associated with the primary memory medium and the secondary memory medium.

A technique for managing cache in a storage system that supports data deduplication renders each of a set of data blocks as multiple sub-blocks and loads a cache-resident digest database on a per-block basis, selectively creating new digest entries in the database for all sub-blocks in a block, but only for blocks that contain no duplicate sub-blocks. Sub-blocks of blocks containing duplicates are excluded. By limiting digest entries to sub-blocks of blocks that contain no duplicates, the storage system limits the size of the digest database, and thus of the cache, while also biasing the contents of the digest database toward entries that are likely to produce deduplication matches in the future.

A method for improving cache hit ratios for selected volumes within a storage system is disclosed. In one embodiment, such a method includes storing, in a cache of a storage system, non-favored storage elements and favored storage elements. The favored storage elements are retained in the cache longer than the non-favored storage elements. The method maintains a non-favored LRU list that contains entries associated with non-favored storage elements and designates an order in which the non-favored storage elements are evicted from the cache. The method also maintains one or more favored LRU lists that contain entries associated with favored storage elements and designate an order in which the favored storage elements are evicted from the cache. Each favored LRU list is associated with favored storage elements that have a different preferred residency time in the cache. A corresponding system and computer program product are also disclosed.

A method for improving cache hit ratios for selected storage elements within a storage system is disclosed. In one embodiment, such a method includes storing, in a cache of a storage system, non-favored storage elements and favored storage elements. The favored storage elements are retained in the cache longer than the non-favored storage elements. The method maintains a first LRU list containing entries associated with non-favored storage elements and designating an order in which the non-favored storage elements are evicted from the cache, and a second LRU list containing entries associated with favored storage elements and designating an order in which the favored storage elements are evicted from the cache. The method moves entries between the first LRU list and the second LRU list as favored storage elements are changed to non-favored storage elements and vice versa. A corresponding system and computer program product are also disclosed.

A cache system includes a cache memory having a plurality of blocks, a dirty line list storing status information of a predetermined number of dirty lines among dirty lines in the plurality of blocks, and a cache controller controlling a data caching operation of the cache memory and providing statuses and variation of statuses of the dirty lines, according to the data caching operation, to the dirty line list. The cache controller performs a control operation to always store status information of a least-recently-used (LRU) dirty line into a predetermined storage location of the dirty line list.

A technique for managing a deduplication digest cache (DDC) includes assigning each digest entry of the DDC to one of multiple entry lists, scoring the entry lists based at least in part on the deduplicability of the data represented by the digest entries in the entry lists, and selecting for eviction from the DDC entries assigned to the lowest-scoring entry list. In this manner, entries assigned to entry lists that perform more poorly in terms of deduplicability tend to be evicted more quickly than entries assigned to entry lists that perform better.