Memverge, Inc.

Ronald S Niles

Yue Li

Robert W Beauchamp

Jun Gan

Chenggong Charles Fan

Dahong Li

Chenggong Fan

A memory image can be captured by generating metadata indicative of a state of volatile memory and/or byte-addressable PMEM at a particular time during execution of a process by an application. This memory image can be persisted without copying the in-memory data into a separate persistent storage by storing the metadata and safekeeping the in-memory data in the volatile memory and/or PMEM. Metadata associated with multiple time-evolved memory images captured can be stored and managed using a linked index scheme. A linked index scheme can be configured in various ways including a full index and a difference-only index. The memory images can be used for various purposes including suspending and later resuming execution of the application process, restoring a failed application to a previous point in time, cloning an application, and recovering an application process to a most recent state in an application log.

Memory image capture

Reduced impact application recovery

A technique is introduced for applying multi-level caching to deploy various types of physical memory to service captured memory calls from an application. The various types of physical memory can include local volatile memory (e.g., dynamic random-access memory), local persistent memory, and/or remote persistent memory. In an example embodiment, a user-space page fault notification mechanism is used to defer assignment of actual physical memory resources until a memory buffer is accessed by the application. After populating a selected physical memory in response to an initial user-space page fault notification, page access information can be monitored to determine which pages continues to be accessed and which pages are inactive to identify candidates for eviction.

Multi-level caching to deploy local volatile memory, local persistent memory, and remote persistent memory

Application recovery using a memory image

Persistent memory image capture

A technique is described for handling forks in operations mapped to direct access persistent memory (PMEM). In an example embodiment, access by a parent operation of an allocated portion of PMEM is monitored to determine a portion of the allocated PMEM that is in use by the parent operation. In response to a fork call indicating that the parent operation will copy itself to create a child operation, a clone of the portion of allocated PMEM is created to facilitate processing of the child operation. The cloned portion of PMEM can be created just before the child operation is created (i.e., pre-fork) or after the child operation is created (i.e., post-fork). To create the clone post-fork, a user-space page fault notification mechanism can be implemented to detect a next buffer access by the child operation and create the clone in response to the detected access.

Fork handling in application operations mapped to direct access persistent memory

A technique is introduced for intercepting memory calls from a user-space application and applying an allocation policy to determine whether such calls are handled using volatile memory such as dynamic random-access memory (DRAM) or persistent memory (PMEM). In an example embodiment, memory calls from an application are intercepted by a memory allocation capture library. Such calls may be to a memory function such as malloc( ) and may be configured to cause a portion of DRAM to be allocated to the application to process a task. The memory allocation capture library then determines whether the intercepted call satisfies capture criteria associated with an allocation policy. If the intercepted call does satisfy the capture criteria, the call is processed to cause a portion of PMEM to be allocated to the application instead of DRAM.

Growing community of inventors

San Jose, CA, United States of America

Ronald S Niles