Method for caching and migrating de-compressed page

A method for memory decompression, comprising:

• receiving, by a buffer device, a data access request to a location within a block of memory of a memory system, wherein data in the block of memory are compressed into a plurality of compressed pages;
• determining a metric based on a number of the compressed pages whose decompressed data are stored in a cache buffer, wherein the metric is associated with a frequency of access to the plurality of compressed pages, wherein the cache buffer of the buffer device is used to store decompressed data of a subset of the plurality of compressed pages;
• determining based on the metric, to decompress additional compressed pages for storage in the cache buffer when the number of the compressed pages whose decompressed data are stored in the cache buffer does not exceed a first threshold;
• decompressing one of the compressed pages containing the location of the data access request for storage in the cache buffer in response to determining to decompress additional compressed pages for storage in the cache buffer;
• decompressing all of the plurality of compressed pages including the one compressed page containing the location of the data access request for storage in an allocated memory space of the memory system in response to determining not to decompress additional compressed pages for storage in the cache buffer;
• determining that a decompressed page dataset, corresponding to a particular compressed page stored in a particular memory space of the block of memory, is overwritten with a different decompressed page dataset;
• compressing the different decompressed page dataset to generate a different compressed page dataset;
• setting a lock bit associated with an entry in the cache buffer corresponding to the decompressed data to prevent eviction of the decompressed data during data migration;
• performing the data migration by writing the different compressed page dataset to the particular compressed page of the particular memory space;
• determining whether the decompressed data has been modified based on a status bit associated with the entry in the cache buffer corresponding to the decompressed data;
• clearing the decompressed data of one of the subset of compressed pages from the cache buffer based on the metric when the status bit indicates the decompressed data has not been modified and the lock bit is not set;
• and
• setting a valid bit associated with the entry in the cache buffer to indicate whether the entry is valid.

A non-transitory computer-readable medium having instructions stored therein, which when executed by a processor, cause the processor to perform operations, the operations comprising:

• receiving a data access request to a location within a block of memory of a memory system, wherein data in the block of memory are compressed into a plurality of compressed pages;
• determining a metric based on a number of the compressed pages whose decompressed data are stored in a cache buffer, wherein the metric is associated with a frequency of access to the plurality of compressed pages, wherein the cache buffer is used to store decompressed data of a subset of the plurality of compressed pages;
• determining, based on the metric, to decompress additional compressed pages for storage in the cache buffer when the number of the compressed pages whose decompressed data are stored in the cache buffer does not exceed a first threshold;
• decompressing one of the compressed pages containing the location of the data access request for storage in the cache buffer in response to determining to decompress additional compressed pages for storage in the cache buffer;
• decompressing all of the plurality of compressed pages including the one compressed page containing the location of the data access request for storage in an allocated memory space of the memory system in response to determining not to decompress additional compressed pages for storage in the cache buffer;
• determining that a decompressed page dataset, corresponding to a particular compressed page stored in a particular memory space of the block of memory, is overwritten with a different decompressed page dataset;
• compressing the different decompressed page dataset to generate a different compressed page dataset;
• setting a lock bit associated with an entry in the cache buffer corresponding to the decompressed data to prevent eviction of the decompressed data during data migration;
• performing the data migration by writing the different compressed page dataset to the particular compressed page of the particular memory space;
• determining whether the decompressed data has been modified based on a status bit associated with the entry in the cache buffer corresponding to the decompressed data;
• clearing the decompressed data of one of the subset of compressed pages from the cache buffer based on the metric when the status bit indicates the decompressed data has not been modified and the lock bit is not set;
• and
• setting a valid bit associated with the entry in the cache buffer to indicate whether the entry is valid.