A cache may store critical cache lines and non-critical cache lines, and may attempt to retain critical cache lines in the cache by, for example, favoring the critical cache lines in replacement data updates, retaining the critical cache lines with a certain probability when victim cache blocks are being selected, etc. Criticality values may be retained at various levels of the cache hierarchy. Additionally, accelerated eviction may be employed if the threads previously accessing the critical cache blocks are viewed as dead.

A processor, including a core; and a cache-coherent memory fabric coupled to the core and having a primary cache agent (PCA) configured to provide a primary access path; and a secondary cache agent (SCA) configured to provide a secondary access path that is redundant to the primary access path, wherein the PCA has a coherency controller configured to maintain data in the secondary access path coherent with data in the main access path.

Described is a data cache implementing hybrid writebacks and writethroughs. A processing system includes a memory, a memory controller, and a processor. The processor includes a data cache including cache lines, a write buffer, and a store queue. The store queue writes data to a hit cache line and an allocated entry in the write buffer when the hit cache line is initially in at least a shared coherence state, resulting in the hit cache line being in a shared coherence state with data and the allocated entry being in a modified coherence state with data. The write buffer requests and the memory controller upgrades the hit cache line to a modified coherence state with data based on tracked coherence states. The write buffer retires the data upon upgrade. The data cache writebacks the data to memory for a defined event.

Methods, systems, and devices for session-based memory operation are described. A memory system may determine that a logical address targeted by a read command is associated with a session table. The memory system may write the session table to a cache based on the logical address being associated with the session table. After writing the session table to the cache, the memory system may use the session table to determine one or more logical-to-physical (L2P) tables and write the one or more L2P tables to the cache. The memory system may use the L2L tables to perform address translation for logical addresses.

A system includes a first counter configured to increment or decrement in response to a triggering event. The first counter is sized to overflow. The system also includes a second counter configured to increment or decrement in response to a triggering event. The first counter and the second counter are merged to form a third counter in response to detecting an overflow triggering event for the first counter. A merge bit indicative of whether the first counter and the second counter are merged changes value in response to merging the first counter and the second counter.

Aspects relate to Input/Output (IO) Memory Management Units (MMUs) that include hardware structures for implementing virtualization. Some implementations allow guests to setup and maintain device IO tables within memory regions to which those guests have been given permissions by a hypervisor. Some implementations provide hardware page table walking capability within the IOMMU, while other implementations provide static tables. Such static tables may be maintained by a hypervisor on behalf of guests. Some implementations reduce a frequency of interrupts or invocation of hypervisor by allowing transactions to be setup by guests without hypervisor involvement within their assigned device IO regions. Devices may communicate with IOMMU to setup the requested memory transaction, and completion thereof may be signaled to the guest without hypervisor involvement. Various other aspects will be evident from the disclosure.

One example method includes a cache eviction operation. Entries in a cache are maintained in an entry list that includes a recent list and a frequent list. When an eviction operation is initiated or triggered, timestamps of last access for the entries are adjusted by corresponding adjustment values. Candidates for eviction are identified based on the adjusted timestamps of last access. At least some of the candidates are evicted from the cache.

An apparatus and method are provided for receiving a request from a plurality of processing units, where multiple of those processing units have associated cache storage. A snoop unit is used to implement a cache coherency protocol when a request is received that identifies a cacheable memory address. The snoop unit has snoop filter storage comprising a plurality of snoop filter tables organized in a hierarchical arrangement. The snoop filter tables comprise a primary snoop filter table at a highest level in the hierarchy, and each snoop filter table at a lower level in the hierarchy forms a backup snoop filter table for an adjacent snoop filter table at a higher level in the hierarchy. Each snoop filter table is arranged as a multi-way set associative storage structure, and each backup snoop filter table has a different number of sets than are provided in the adjacent snoop filter table.

An encoding device and a decoding device use linear and nonlinear codes for encoding and decoding system data for a storage device. The encoding device includes a linear encoder for encoding first data to generate encoded data and a nonlinear transformer for transforming the encoded data with second data to generate output data. The first data includes data on a physical address corresponding to a logical address. The second data includes the logical address and a timestamp value indicating a version of map data mapping between the logical address and the physical address.

A device includes a data path, a first interface configured to receive a first memory access request from a first peripheral device, and a second interface configured to receive a second memory access request from a second peripheral device. The device further includes an arbiter circuit configured to, in a first clock cycle, a pre-arbitration winner between a first memory access request and a second memory access request based on a first number of credits allocated to a first destination device and a second number of credits allocated to a second destination device. The arbiter circuit is further configured to, in a second clock cycle select a final arbitration winner from among the pre-arbitration winner and a subsequent memory access request based on a comparison of a priority of the pre-arbitration winner and a priority of the subsequent memory access request.