Abstract: Techniques for implementing a hardware-based cache controller in, e.g., a tiered memory computer system are provided. In one set of embodiments, the cache controller can flexibly operate in a number of different modes that aid the OS/hypervisor of the computer system in managing and optimizing its use of the system's memory tiers. In another set of embodiments, the cache controller can implement a hardware architecture that enables it to significantly reduce the probability of tag collisions, decouple cache capacity management from cache lookup and allocation, and handle multiple concurrent cache transactions.

Abstract: Techniques for implementing a hardware-based cache controller in, e.g., a tiered memory computer system are provided. In one set of embodiments, the cache controller can flexibly operate in a number of different modes that aid the OS/hypervisor of the computer system in managing and optimizing its use of the system's memory tiers. In another set of embodiments, the cache controller can implement a hardware architecture that enables it to significantly reduce the probability of tag collisions, decouple cache capacity management from cache lookup and allocation, and handle multiple concurrent cache transactions.

Abstract: Techniques for implementing a hardware-based cache controller in, e.g., a tiered memory computer system are provided. In one set of embodiments, the cache controller can flexibly operate in a number of different modes that aid the OS/hypervisor of the computer system in managing and optimizing its use of the system's memory tiers. In another set of embodiments, the cache controller can implement a hardware architecture that enables it to significantly reduce the probability of tag collisions, decouple cache capacity management from cache lookup and allocation, and handle multiple concurrent cache transactions.

Abstract: A memory hierarchy includes a first memory and a second memory that is at a lower position in the memory hierarchy than the first memory. A method of managing the memory hierarchy includes: observing, over a first period of time, accesses to pages of the first memory; in response to determining that no page in a first group of pages was accessed during the first period of time, moving each page in the first group of pages from the first memory to the second memory; and in response to determining that the number of pages in other groups of pages of the first memory, which were accessed during the first period of time, is less than a threshold number of pages, moving each page in the other group of pages, that was not accessed during the first period of time from the first memory to the second memory.

Abstract: In one set of embodiments, a hardware module of a computer system can receive a stream of addresses corresponding to memory units being accessed by a central processing unit (CPU) of the computer system. The hardware module can further generate a frequency estimate for each address in the stream of addresses, the frequency estimate being indicative of a number of times a memory unit identified by the address has been accessed by the CPU, and can determine, based on the generated frequency estimates, a set of n most frequently accessed memory units.

Abstract: The state of cache lines transferred into an out of caches of processing hardware is tracked by monitoring hardware. The method of tracking includes monitoring the processing hardware for cache coherence events on a coherence interconnect between the processing hardware and monitoring hardware, determining that the state of a cache line has changed, and updating a hierarchical data structure to indicate the change in the state of said cache line. The hierarchical data structure includes a first level data structure including first bits, and a second level data structure including second bits, each of the first bits associated with a group of second bits. The step of updating includes setting one of the first bits and one of the second bits in the group corresponding to the first bit that is being set, according to an address of said cache line.

Abstract: In one set of embodiments, a hardware module of a computer system can receive a stream of addresses corresponding to memory units being accessed by a central processing unit (CPU) of the computer system. The hardware module can further generate a frequency estimate for each address in the stream of addresses, the frequency estimate being indicative of a number of times a memory unit identified by the address has been accessed by the CPU, and can determine, based on the generated frequency estimates, a set of n most frequently accessed memory units.

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: 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: The state of cache lines transferred into an out of caches of processing hardware is tracked by monitoring hardware. The method of tracking includes monitoring the processing hardware for cache coherence events on a coherence interconnect between the processing hardware and monitoring hardware, determining that the state of a cache line has changed, and updating a hierarchical data structure to indicate the change in the state of said cache line. The hierarchical data structure includes a first level data structure including first bits, and a second level data structure including second bits, each of the first bits associated with a group of second bits. The step of updating includes setting one of the first bits and one of the second bits in the group corresponding to the first bit that is being set, according to an address of said cache line.