Abstract: Disclosed is a method for performing write-back operations to maintain coherence of remote memories in a memory pool. When a local application makes a request for a page of memory that is in the memory pool but not local, a device obtains the page through its RDMA facility and thereafter keeps track of the page for any changes made by the application to the page by storing the page locally and monitoring cache coherency events of cache lines that make up the page. If a requested page become dirty, then periodically the dirty cache lines of the dirty page are written back to the remote memory from which the pages were obtained. In addition, all dirty cache lines are written back when the local memory storing the page becomes full or the application closes a region containing the page.

Abstract: A virtual machine running on a source host is live migrated to a destination host. The source host includes a first processing node with a first processing hardware and a first memory, and a second processing node with a second processing hardware and a second memory. While the virtual machine is running on the first processing hardware, the second processing hardware tracks cache lines of the first processing hardware that become dirty as a result of write operations performed on one or more memory pages of the virtual machine. The dirty cache lines are copied to the destination host in units of a cache line or groups of cache lines.

Abstract: Described herein is a method for tracking changes to memory locations made by an application. In one embodiment, the application decides to start tracking and sends a list of virtual memory pages to be tracked to an operating system via an interface. The operating system converts the list of virtual memory pages to a list of physical addresses and sends the list of physical addresses to a hardware unit which performs the tracking by detecting write backs on a coherence interconnect coupled to the hardware unit. After the application ends tracking, the application requests a list of dirty cache lines. In response to the request, the operating system obtains the list of dirty cache lines from the hardware unit and adds the list to a buffer that the application can read. In other embodiments, the operating system can perform the tracking without the application making the request.

Abstract: Disclosed is a technique in which an application can record changes it makes to physical memory. In the technique, the application specifies a virtual memory region which is converted to a plurality of cache lines, each of which is monitored for changes by a device connected to a coherence interconnect coupled to the processor caches. The application sends a start signal to start the logging process and an end signal to stop the process. During the logging process, when a change occurs to one of the cache lines, an undo entry corresponding to the change is created and entered into a transaction log residing in persistent memory. The transaction log containing the undo entries makes the set of changes recorded in the transaction log atomic. If a failure occurs, the recorded changes can be undone as if they never occurred.

Abstract: Techniques for achieving application high availability via application-transparent battery-backed replication of persistent data are provided. In one set of embodiments, a computer system can detect a failure that causes an application of the computer system to stop running. In response to detecting the failure, the computer system can copy persistent data written by the application and maintained locally at the computer system to one or more remote destinations, where the copying is performed in a manner that is transparent to the application and while the computer system runs on battery power. The application can then be restarted on another computer system using the copied data.

Abstract: A virtual-machine-based system that identifies an application or process in a virtual machine in order to locate resources associated with the identified application. Access to the located resources is then controlled based on a context of the identified application. Those applications without the necessary context will have a different view of the resource.

Abstract: Techniques for implementing application fault tolerance via battery-backed replication of volatile state are provided. In one set of embodiments, a primary host system can detect a failure that causes an application of the primary host system to stop running. In response to detecting the failure, the primary host system can replicate volatile state that is used by the application to a secondary host system, where the secondary host system maintains a copy of the application, and where execution of the application is failed over to the copy on the secondary host system using the replicated volatile state.

Abstract: Techniques for achieving application high availability via application-transparent battery-backed replication of persistent data are provided. In one set of embodiments, a computer system can detect a failure that causes an application of the computer system to stop running. In response to detecting the failure, the computer system can copy persistent data written by the application and maintained locally at the computer system to one or more remote destinations, where the copying is performed in a manner that is transparent to the application and while the computer system runs on battery power. The application can then be restarted on another computer system using the copied data.

Abstract: Techniques for achieving application high availability via crash-consistent asynchronous replication of persistent data are provided. In one set of embodiments, an application running on a computer system can, during runtime of the application: write persistent data to a local nonvolatile data store of the computer system, write one or more log entries comprising the persistent data to a local log region of the computer system, and asynchronously copy the one or more log entries to one or more remote destinations. Then, upon detecting a failure that prevents the application from continuing execution, the computer system can copy the local log region or a remaining portion thereof to the one or more remote destinations, where the copying is performed while the computer system runs on battery power and where the application is restarted on another computer system using a persistent state derived from the copied log entries.

Abstract: Described herein is a method for tracking changes made by an application. Embodiments include determining, by a processor, a write-back of a cache line from a hardware unit associated with a socket of a plurality of sockets to a page table entry of a page table in a memory location associated with the processor. Embodiments include adding, by the processor, the cache line to a list of dirty cache lines. Embodiments include, for each respective cache line in the list of dirty cache lines, identifying, by the processor, a memory location associated with a respective socket of the plurality of sockets corresponding to the respective cache line and updating, by the processor, an entry of a page table replica at the memory location based on the respective cache line.

Abstract: Techniques for using commit coalescing when performing micro-journal-based transaction logging are provided. In one embodiment a computer system can maintain, in a volatile memory, a globally ascending identifier, a first list of free micro-journals, and a second list of in-flight micro-journals. The computer system can further receive a transaction comprising a plurality of modifications to data or metadata stored in the byte-addressable persistent memory, select a micro-journal from the first list, obtain a lock on the globally ascending identifier, write a current value of the globally ascending identifier as a journal commit identifier into a header of the micro-journal, and write journal entries into the micro-journal corresponding to the plurality of modifications included in the transaction. The computer system can then commit the micro-journal to the byte-addressable persistent memory, increment the current value of the globally ascending identifier, and release the lock.

Abstract: The disclosure provides an approach for creating a pool of memory out of local memories of host machines, and providing that pool for the hosts to use. The pool is managed by a controller that keeps track of memory usage and allocated memory among hosts. The controller allocates or reclaims memory between hosts, as needed by the hosts. Memory allocated from a second host to a first host may then be divided into smaller portions by the first host, and further allocated to virtual machines executing within the first host.

Abstract: To generate a checkpoint for a virtual machine (VM), first, while the VM is still running, a copy-on-write (COW) disk file is created pointing to a parent disk file that the VM is using. Next, the VM is stopped, the VM's memory is marked COW, the device state of the VM is saved to memory, the VM is switched to use the COW disk file, and the VM begins running again for substantially the remainder of the checkpoint generation. Next, the device state that was stored in memory and the unmodified VM memory pages are saved to a checkpoint file. Also, a copy may be made of the parent disk file for retention as part of the checkpoint, or the original parent disk file may be retained as part of the checkpoint. If a copy of the parent disk file was made, then the COW disk file may be committed to the original parent disk file.

Abstract: Techniques for using commit coalescing when performing micro-journal-based transaction logging are provided. In one embodiment a computer system can maintain, in a volatile memory, a globally ascending identifier, a first list of free micro-journals, and a second list of in-flight micro-journals. The computer system can further receive a transaction comprising a plurality of modifications to data or metadata stored in the byte-addressable persistent memory, select a micro-journal from the first list, obtain a lock on the globally ascending identifier, write a current value of the globally ascending identifier as a journal commit identifier into a header of the micro-journal, and write journal entries into the micro-journal corresponding to the plurality of modifications included in the transaction. The computer system can then commit the micro-journal to the byte-addressable persistent memory, increment the current value of the globally ascending identifier, and release the lock.

Abstract: A module for rewriting application code as a failure-atomic transaction is disclosed. An application delineates a code fragment that is to become a failure-atomic transaction by writing a tx_begin( ) and tx_end( ) functions into its code. A module detects the tx_begin( ) and tx_end( ) functions and rewrites the code fragment as a failure-atomic transaction. The rewritten code is then available to be executed by the application. The rewritten code stores values and locations of stores to persistent memory locations so that the transaction can be either undone or redone in the case of an application error or a power failure. If the transaction is an undo type of transaction, the application can be rolled back to a state prior to the failure. If the transaction is a redo type of transaction, the application can be advanced to a correct state after the error.

Abstract: Disclosed are embodiments for running an application on a local processor when the application is dependent on pages not locally present but contained in a remote host. The system is informed that the pages on which the application depends are locally present. While running, the application encounters a cache miss and a cache line satisfying the miss from the remote host is obtained and provided to the application. Alternatively, the page containing the cache line satisfying the miss is obtained and the portion of the page not including the cache line is stored locally while the cache line is provided to the application. The cache miss is discovered by monitoring coherence events on a coherence interconnect connected to the local processor. In some embodiments, the cache misses are tracked and provide a way to predict a set of pages to be pre-fetched in anticipation of the next cache misses.

Abstract: Disclosed is a technique in which an application can record changes it makes to physical memory. In the technique, the application specifies a virtual memory region which is converted to a plurality of cache lines, each of which is monitored for changes by a device connected to a coherence interconnect coupled to the processor caches. The application sends a start signal to start the logging process and an end signal to stop the process. During the logging process, when a change occurs to one of the cache lines, an undo entry corresponding to the change is created and entered into a transaction log residing in persistent memory. The transaction log containing the undo entries makes the set of changes recorded in the transaction log atomic. If a failure occurs, the recorded changes can be undone as if they never occurred.

Abstract: Described herein is a method for tracking changes to memory locations made by an application. In one embodiment, the application decides to start tracking and sends a list of virtual memory pages to be tracked to an operating system via an interface. The operating system converts the list of virtual memory pages to a list of physical addresses and sends the list of physical addresses to a hardware unit which performs the tracking by detecting write backs on a coherence interconnect coupled to the hardware unit. After the application ends tracking, the application requests a list of dirty cache lines. In response to the request, the operating system obtains the list of dirty cache lines from the hardware unit and adds the list to a buffer that the application can read. In other embodiments, the operating system can perform the tracking without the application making the request.

Abstract: A module for rewriting application code as a failure-atomic transaction is disclosed. An application delineates a code fragment that is to become a failure-atomic transaction by writing a tx_begin( ) and tx_end( ) functions into its code. A module detects the tx_begin( ) and tx_end( ) functions and rewrites the code fragment as a failure-atomic transaction. The rewritten code is then available to be executed by the application. The rewritten code stores values and locations of stores to persistent memory locations so that the transaction can be either undone or redone in the case of an application error or a power failure. If the transaction is an undo type of transaction, the application can be rolled back to a state prior to the failure. If the transaction is a redo type of transaction, the application can be advanced to a correct state after the error.

Abstract: Described herein is a method for tracking changes made by an application. Embodiments include determining, by a processor, a write-back of a cache line from a hardware unit associated with a socket of a plurality of sockets to a page table entry of a page table in a memory location associated with the processor. Embodiments include adding, by the processor, the cache line to a list of dirty cache lines. Embodiments include, for each respective cache line in the list of dirty cache lines, identifying, by the processor, a memory location associated with a respective socket of the plurality of sockets corresponding to the respective cache line and updating, by the processor, an entry of a page table replica at the memory location based on the respective cache line.