A method for processing a memory page in memory, where the memory page in the memory includes an idle single-level cell (SLC) memory page, an active SLC memory page, an inactive SLC memory page, and a multi-level cell (MLC) memory page, and when a quantity of idle SLC memory pages of any virtual machine (VM) is less than a specified threshold, the processing method includes converting one idle SLC memory page to two MLC memory pages, copying data in two inactive SLC memory pages to the two converted MLC memory pages, and releasing storage space of the two inactive SLC memory pages to obtain two idle SLC memory pages.

A method for processing a memory page in memory, where the memory page in the memory includes an idle single-level cell (SLC) memory page, an active SLC memory page, an inactive SLC memory page, and a multi-level cell (MLC) memory page, and when a quantity of idle SLC memory pages of any virtual machine (VM) is less than a specified threshold, the processing method includes converting one idle SLC memory page to two MLC memory pages, copying data in two inactive SLC memory pages to the two converted MLC memory pages, and releasing storage space of the two inactive SLC memory pages to obtain two idle SLC memory pages.

A system and method for efficiently caching metadata in a storage system. Addresses from a plurality of I/O accesses to the storage system are captured and then a frequency domain representation of the addresses is generated. The frequency domain representation is used to measure the randomness of the various applications which are accessing the storage system. Scores are generated based on the measure of randomness, and scores are assigned to the various regions of the logical address space. Scores are then assigned to the metadata pages which are stored in the cache based on the region of the logical address space to which the metadata pages correspond. The scores are used when determining which metadata pages to evict from the cache. The cache will attempt to evict those metadata pages which correspond to regions of the logical address space that are servicing random I/O accesses.

A system and method for efficiently caching metadata in a storage system. Addresses from a plurality of I/O accesses to the storage system are captured and then a frequency domain representation of the addresses is generated. The frequency domain representation is used to measure the randomness of the various applications which are accessing the storage system. Scores are generated based on the measure of randomness, and scores are assigned to the various regions of the logical address space. Scores are then assigned to the metadata pages which are stored in the cache based on the region of the logical address space to which the metadata pages correspond. The scores are used when determining which metadata pages to evict from the cache. The cache will attempt to evict those metadata pages which correspond to regions of the logical address space that are servicing random I/O accesses.

One embodiment of the present invention sets forth a computer-implemented method for migrating a memory page from a first memory to a second memory. The method includes determining a first page size supported by the first memory. The method also includes determining a second page size supported by the second memory. The method further includes determining a use history of the memory page based on an entry in a page state directory associated with the memory page. The method also includes migrating the memory page between the first memory and the second memory based on the first page size, the second page size, and the use history.

Systems and methods for predictive cache replacement policies are provided. In particular, some embodiments dynamically capture and predict access patterns of data to determine which data should be evicted from the cache. A novel tree data structure can be dynamically built that allows for immediate use in the identification of developing patterns and the eviction determination. In some cases, the data can be dynamically organized into histograms, strings, and other representations allowing traditional analysis techniques to be applied. Data organized into histogram-like structures can also be converted into strings allowing for well-known string pattern recognition analysis. The pattern recognition and prediction techniques disclosed also have applications outside of caching.

Systems and methods for predictive cache replacement policies are provided. In particular, some embodiments dynamically capture and predict access patterns of data to determine which data should be evicted from the cache. A novel tree data structure can be dynamically built that allows for immediate use in the identification of developing patterns and the eviction determination. In some cases, the data can be dynamically organized into histograms, strings, and other representations allowing traditional analysis techniques to be applied. Data organized into histogram-like structures can also be converted into strings allowing for well-known string pattern recognition analysis. The pattern recognition and prediction techniques disclosed also have applications outside of caching.

A cache apparatus stores part of a plurality of accessible data blocks into a cache area. A calculation part calculates, for each pair of data blocks of the plurality of data blocks, an expected value of the number of accesses made after one of the data blocks is accessed until the other of the data blocks is accessed, on the basis of a probability that when each of the plurality of data blocks is accessed, each data block that is likely to be accessed next is accessed next. When a data block is read from outside the cache area, a determination part determines a data block to be discarded from the cache area, on the basis of the expected value of the number of accesses made after the read data block is accessed until each of the plurality of data blocks is accessed.

An information processing system comprising a storage device and an information processing device, wherein the information processing device includes a data holding unit which holds first data, a first detection unit which detects a first state of access, and a transmission unit which transmits the first state of access detected by the first detection unit to the storage device, and the storage device includes a storage unit which stores second data, a reception unit which receives the first state of access transmitted from the transmission unit, a second detection unit which detects a second state of access, which is a state of access to the second data, and a control unit which rearranges the second data in the storage unit on the basis of the states of access.

An information processing system comprising a storage device and an information processing device, wherein the information processing device includes a data holding unit which holds first data, a first detection unit which detects a first state of access, and a transmission unit which transmits the first state of access detected by the first detection unit to the storage device, and the storage device includes a storage unit which stores second data, a reception unit which receives the first state of access transmitted from the transmission unit, a second detection unit which detects a second state of access, which is a state of access to the second data, and a control unit which rearranges the second data in the storage unit on the basis of the states of access.