Abstract: Disclosed are various embodiments for improving the resiliency and performance for clustered memory. A computing device can mark a page of the memory as being reclaimed. The computing device can then set the page of the memory as read-only. Next, the computing device can submit a write request for the contents of the page to individual ones of a plurality of memory hosts. Subsequently, the computing device can receive individual confirmations of a successful write of the page from the individual ones of the plurality of memory hosts. Then, the computing device can mark the page as free in response to receipt of the individual confirmations of the successful write from the individual ones of the plurality of memory hosts.

Abstract: Techniques for implementing high availability for persistent memory are provided. In one embodiment, a first computer system can detect an alternating current (AC) power loss/cycle event and, in response to the event, can save data in a persistent memory of the first computer system to a memory or storage device that is remote from the first computer system and is accessible by a second computer system. The first computer system can then generate a signal for the second computer system subsequently to initiating or completing the save process, thereby allowing the second computer system to restore the saved data from the memory or storage device into its own persistent memory.

Abstract: Disclosed are various embodiments for decreasing the amount of time spent processing interrupts by switching contexts in parallel with processing an interrupt. An interrupt request can be received during execution of a process in a less privileged user mode. Then, the current state of the process can be saved. Next, a switch from the less privileged mode to a more privileged mode can be made. The interrupt request is then processed while in the more privileged mode. Subsequently or in parallel, and possibly prior to completion of the processing the interrupt request, another switch from the more privileged mode to the less privileged mode can be made.

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: Disclosed are various embodiments for improving resiliency and performance of clustered memory. A computing device can acquire a chunk of byte-addressable memory from a cluster memory host. The computing device can then identify an active set of allocated memory pages and an inactive set of allocated memory pages for a process executing on the computing device. Next, the computing device can store the active set of allocated memory pages for the process in the memory of the computing device. Finally, the computing device can store the inactive set of allocated memory pages for the process in the chunk of byte-addressable memory of the cluster memory host.

Abstract: Disclosed are various embodiments for improving the resiliency and performance of cluster memory. First, a computing device can submit a write request to a byte-addressable chunk of memory stored by a memory host, wherein the byte-addressable chunk of memory is read-only. Then, the computing device can determine that a page-fault occurred in response to the write request. Next, the computing device can copy a page associated with the write request from the byte-addressable chunk of memory to the memory of the computing device. Subsequently, the computing device can free the page from the memory host. Then, the computing device can update a page table entry for the page to refer to a location of the page in the memory of the computing device.

Abstract: Techniques for implementing hardware-assisted memory disaggregation with recovery from network failures/problems are provided. In one set of embodiments, a hardware controller of a computer system can maintain a copy of a “remote memory” of the computer system (i.e., a section of the physical memory address space of the computer system that maps to a portion of the physical system memory of a remote computer system) in a local backup memory. The backup memory may be implemented using a non-volatile memory that is slower, but also less expensive, than conventional dynamic random-access memory (DRAM). Then, if the hardware controller is unable to retrieve data in the remote memory from the remote computer system within a specified time window due to, e.g., a network failure or other problem, the hardware controller can retrieve the data from the backup memory, thereby avoiding a hardware error condition (and potential application/system crash).

Abstract: Disclosed are various embodiments for improving the resiliency and performance for clustered memory. A computing device can mark a page of the memory as being reclaimed. The computing device can then set the page of the memory as read-only. Next, the computing device can submit a write request for the contents of the page to individual ones of a plurality of memory hosts. Subsequently, the computing device can receive individual confirmations of a successful write of the page from the individual ones of the plurality of memory hosts. Then, the computing device can mark the page as free in response to receipt of the individual confirmations of the successful write from the individual ones of the plurality of memory hosts.

Abstract: Disclosed are various embodiments for improving the resiliency and performance of clustered memory. A computing device can generate at least one parity page from at least a first local page and a second local page. The computing device can then submit a first write request for the first local page to a first one of a plurality of memory hosts. The computing device can also submit a second write request for the second local page to a second one of the plurality of memory hosts. Additionally, the computing device can submit a third write request for the parity page to a third one of the plurality of memory hosts.

Abstract: Disclosed are various embodiments for high throughput reclamation of pages in memory. A first plurality of pages in a memory of the computing device are identified to reclaim. In addition, a second plurality of pages in the memory of the computing device are identified to reclaim. The first plurality of pages are prepared for storage on a swap device of the computing device. Then, a write request is submitted to a swap device to store the first plurality of pages. After submission of the write request, the second plurality of pages are prepared for storage on the swap device while the swap device completes the write request.

Abstract: Techniques for implementing hardware-assisted memory disaggregation with recovery from network failures/problems are provided. In one set of embodiments, a hardware controller of a computer system can maintain a copy of a “remote memory” of the computer system (i.e., a section of the physical memory address space of the computer system that maps to a portion of the physical system memory of a remote computer system) in a local backup memory. The backup memory may be implemented using a non-volatile memory that is slower, but also less expensive, than conventional dynamic random-access memory (DRAM). Then, if the hardware controller is unable to retrieve data in the remote memory from the remote computer system within a specified time window due to, e.g., a network failure or other problem, the hardware controller can retrieve the data from the backup memory, thereby avoiding a hardware error condition (and potential application/system crash).

Abstract: In a computer system, a processor and an I/O device controller communicate with each other via a coherence interconnect and according to a cache coherence protocol. Registers of the I/O device controllers are mapped to the cache coherent memory space to allow the processor to treat the registers as cacheable memory. As a result, latency of processor commands executed by the I/O device controller is decreased, and size of data stored in the I/O device controller that can be accessed by the processor is increased from the size of a single register to the size of an entire cache line.

Abstract: Memory pages of a local application program are prefetched from a memory of a remote host. A method of prefetching the memory pages from the remote memory includes detecting that a cache-line access made by a processor executing the local application program is an access to a cache line containing page table data of the local application program, identifying data pages that are referenced by the page table data, and fetching the identified data pages from the remote memory and storing the fetched data pages in a local memory.

Abstract: Disclosed are various embodiments for optimized memory tiering. A first page can be allocated in a first memory for a process, the first memory being associated with a first memory tier. Accesses of the first page by the process during execution of the process can be monitored. Then, accesses of the first page by the process during execution of the process can be compared to an allocation policy to make a first determination to move the contents of the first page from the first memory to a second memory associated with a second memory tier. Next, the contents of the first page can be copied from the first memory to a second page in the second memory in response to the first determination.

Abstract: Disclosed are various embodiments for optimized memory tiering. An ideal tier size for a first memory and an ideal tier size for a second memory can be determined for a process. Then, a host computing device can be identified that can accommodate the ideal tier size for the first memory and the second memory. Subsequently, the process can be assigned to the host computing device.

Abstract: Disclosed are various embodiments for optimizing the migration of pages of memory servers in cluster memory systems. To begin, a computing device can mark in a page table of the computing device that a page stored on a first memory host is not present. Then, the computing device can flush a translation lookaside buffer of the computing device. Next, the computing device can copy the page from the first memory host to a second memory host. Moving on, the computing device can update a page mapping table to reflect that the page is stored in the second memory host. Then, the computing device can mark in the page table of the computing device that the page stored in the second memory host is present. Subsequently, the computing device can discard the page stored on the first memory host.

Abstract: A method of performing a copy-on-write on a shared memory page is carried out by a device communicating with a processor via a coherence interconnect. The method includes: adding a page table entry so that a request to read a first cache line of the shared memory page includes a cache-line address of the shared memory page and a request to write to a second cache line of the shared memory page includes a cache-line address of a new memory page; in response to the request to write to the second cache line, storing new data of the second cache line in a second memory and associating the second cache-line address with the new data stored in the second memory; and in response to a request to read the second cache line, reading the new data of the second cache line from the second memory.

Abstract: Disclosed are various embodiments for optimizing the migration of processes or virtual machines in cluster memory systems. To begin, a first computing device can identify a set of pages allocated to a process or virtual machine hosted by the first computing device. Then, the first computing device can identify a subset of the allocated pages that have been accessed with a least a predefined frequency. Next, the first computing device can copy the subset of the allocated pages to a second computing device. Subsequently, the first computing device can copy a page mapping table to the second computing device, the page mapping table specifying which pages in the set of pages allocated to the process or virtual machine are stored by a memory host. Finally, the first computing device can copy remaining ones of the allocated pages to the second computing device.

Abstract: A device tracks accesses to pages of code executed by processors and modifies a portion of the code without terminating the execution of the code. The device is connected to the processors via a coherence interconnect and a local memory of the device stores the code pages. As a result, any requests to access cache lines of the code pages made by the processors will be placed on the coherence interconnect, and the device is able to track any cache-line accesses of the code pages by monitoring the coherence interconnect. In response to a request to read a cache line having a particular address, a modified code portion is returned in place of the code portion stored in the code pages.

Abstract: While an application or a virtual machine (VM) is running, a device tracks accesses to cache lines to detect access patterns that indicate security attacks, such as cache-based side channel attacks or row hammer attacks. To enable the device to detect accesses to cache lines, the device is connected to processors via a coherence interconnect, and the application/VM data is stored in a local memory of the device. The device collects the cache lines of the application/VM data that are accessed while the application/VM is running into a buffer and the buffer is analyzed for access patterns that indicate security attacks.