Abstract: The memory module includes front and back faces. Multiple devices are disposed on each of the faces. A first control line serially connects a first group of devices on both the front and back faces so that the first group of devices commonly contribute multiple bits to a data bus. A second control line serially connects a second group of devices on both the front and back faces so that the second group of devices commonly contribute multiple bits to a data bus.

Abstract: A memory bus with a first bus segment coupled to a memory controller that includes control logic and a first memory device, a second bus segment coupled to a second memory device, and a switch between the first bus segment and the second bus segment. The control logic outputs control information to the switch to selectively decouple the first bus segment and the second bus segment to effect a change in the length of the memory bus to enable data transfer with respect to the first memory device at a first data rate. Additionally, the control logic may output control information to the switch to selectively couple the first bus segment and the second bus segment to increase the length of the memory bus to enable data transfer with respect to the second memory device at a second data rate that is slower than the first data rate.

Abstract: In a system, a memory bus has a first bus segment coupled to a memory controller that includes control logic and a first memory device, a second bus segment coupled to a second memory device, and a switch to selectively couple and decouple the first bus segment and the second bus segment in response to control information from the control logic. Note that the control logic may output control information to the switch to selectively decouple the first bus segment and the second bus segment to effect a change in an electrical length of the memory bus to enable data transfer with respect to the first memory device at a first data rate. Additionally, the control logic may output control information to the switch to selectively couple the first bus segment and the second bus segment to effect another change in the electrical length of the memory bus to enable data transfer with respect to the second memory device at a second data rate that is slower than the first data rate.

Abstract: The memory module includes front and back faces. Multiple devices are disposed on each of the faces. A first control line serially connects a first group of devices on both the front and back faces so that the first group of devices commonly contribute multiple bits to a data bus. A second control line serially connects a second group of devices on both the front and back faces so that the second group of devices commonly contribute multiple bits to a data bus.

Abstract: A cache-coherence protocol distributes atomic operations among multiple processors (or processor cores) that share a memory space. When an atomic operation that includes an instruction to modify data stored in the shared memory space is directed to a first processor that does not have control over the address(es) associated with the data, the first processor sends a request, including the instruction to modify the data, to a second processor. Then, the second processor, which already has control of the address(es), modifies the data. Moreover, the first processor can immediately proceed to another instruction rather than waiting for the address(es) to become available.

Abstract: A method of operating a memory device includes receiving first and second sets of bits to be stored in multi-level cells in the device. A multi-level encoding is selected from among a plurality of multi-level encodings for storing the first and second sets of bits in the multi-level cells. Each multi-level encoding includes at least four encoding levels for a respective multi-level cell. Respective multi-level encodings have respective costs associated with programming the first and second sets of bits into the multi-level cells in accordance with the respective multi-level encodings. The multi-level encoding is selected based on the respective costs of the respective encodings. The first and second sets of bits are encoded in accordance with the selected multi-level encoding to produce encoded data for storage in the device such that a respective multi-level cell stores respective bits from both the first and second sets of bits.

Abstract: The memory module includes front and back faces. Multiple devices are disposed on each of the faces. A first control line serially connects a first group of devices on both the front and back faces so that the first group of devices commonly contribute multiple bits to a data bus. A second control line serially connects a second group of devices on both the front and back faces so that the second group of devices commonly contribute multiple bits to a data bus.

Abstract: A system that calibrates timing relationships between signals involved in performing write operations is described. This system includes a memory controller which is coupled to a set of memory chips, wherein each memory chip includes a phase detector configured to calibrate a phase relationship between a data-strobe signal and a clock signal received at the memory chip from the memory controller during a write operation. Furthermore, the memory controller is configured to perform one or more write-read-validate operations to calibrate a clock-cycle relationship between the data-strobe signal and the clock signal, wherein the write-read-validate operations involve varying a delay on the data-strobe signal relative to the clock signal by a multiple of a clock period.

Abstract: The memory module includes front and back faces. Multiple devices are disposed on each of the faces. A first control line serially connects a first group of devices on both the front and back faces so that the first group of devices commonly contribute multiple bits to a data bus. A second control line serially connects a second group of devices on both the front and back faces so that the second group of devices commonly contribute multiple bits to a data bus.

Abstract: In a system, a memory bus has a first bus segment coupled to a memory controller that includes control logic and a first memory device, a second bus segment coupled to a second memory device, and a switch to selectively couple and decouple the first bus segment and the second bus segment in response to control information from the control logic. Note that the control logic may output control information to the switch to selectively decouple the first bus segment and the second bus segment to effect a change in an electrical length of the memory bus to enable data transfer with respect to the first memory device at a first data rate. Additionally, the control logic may output control information to the switch to selectively couple the first bus segment and the second bus segment to effect another change in the electrical length of the memory bus to enable data transfer with respect to the second memory device at a second data rate that is slower than the first data rate.

Abstract: Systems and methods for reducing heat flux in memory systems are described. In various embodiments, heat flux reductions are achieved by manipulating the device IDs of individual memory devices that comprise a memory module. Through the various described techniques, the per-face heat flux can be desirably reduced. Further, in some embodiments, reductions in heat flux are achieved by providing control lines that operably connect memory devices on different faces of a memory module.

Abstract: A system that calibrates timing relationships between signals involved in performing write operations is described. This system includes a memory controller which is coupled to a set of memory chips, wherein each memory chip includes a phase detector configured to calibrate a phase relationship between a data-strobe signal and a clock signal received at the memory chip from the memory controller during a write operation. Furthermore, the memory controller is configured to perform one or more write-read-validate operations to calibrate a clock-cycle relationship between the data-strobe signal and the clock signal, wherein the write-read-validate operations involve varying a delay on the data-strobe signal relative to the clock signal by a multiple of a clock period.

Abstract: A memory controller monitors requests from one or more computer subsystems and issues one or more prefetch commands if the memory controller detects that the memory system is idle after a period of activity, or if a prefetch buffer read hit occurs. In some embodiments, results of a prefetching operations are stored in a prefetch buffer configured to provide an automatic aging mechanism, which evicts prefetched data from time to time. The prefetched data in the prefetch buffer is released and sent back to the requester in order with respect to previous memory access requests.

Abstract: A memory system having multiple memory devices reduces average access latency by enabling different latencies for different regions of physical memory, providing an address map conducive to placing frequently accessed memory addresses into the lowest latency regions of physical memory; and assigning the frequently accessed memory addresses to the lowest latency regions of physical memory.

Abstract: A memory controller controls access to, and the power state of a plurality of dynamic memory devices. A cache in the memory controller stores entries that indicate a current power state for a subset of the dynamic memory devices. Device state lookup logic responds to a memory access request by retrieving first information from an entry, if any, in the cache corresponding to a device address in the memory access request. The device state lookup logic generates a miss signal when the cache has no entry corresponding to the device address. It also retrieves second information indicating whether the cache is currently storing a maximum allowed number of entries for devices in a predefined mid-power state. Additional logic converts the first and second information and miss signal into at least one command selection signal and at least one update control signal. Cache update logic updates information stored in the cache in accordance with the at least one update control signal.

Abstract: A memory system includes physical memory devices or ranks of memory devices that can be set to reduced power modes. In one embodiment, a hardware memory controller receives memory instructions in terms of a logical address space. In response to the relative usages of different addresses within the logical address space, the memory controller maps the logical address space to physical memory in a way that reduces the number of memory devices that are being used. Other memory devices are then set to reduced power modes. In another embodiment, an operating system maintains a free page list indicating portions of physical memory that are not currently allocated. The operating system periodically sorts this list by group, where each group corresponds to a set or rank of memory devices. The groups are sorted in order from those receiving the heaviest usage to those receiving the lightest usage.

Abstract: A memory controller controls access to, and the power state of a plurality of dynamic memory devices. A cache in the memory controller stores entries that indicate a current power state for a subset of the dynamic memory devices. Device state lookup logic responds to a memory access request by retrieving first information from an entry, if any, in the cache corresponding to a device address in the memory access request. The device state lookup logic generates a miss signal when the cache has no entry corresponding to the device address. It also retrieves second information indicating whether the cache is currently storing a maximum allowed number of entries for devices in a predefined mid-power state. Additional logic converts the first and second information and miss signal into at least one command selection signal and at least one update control signal. Cache update logic updates information stored in the cache in accordance with the at least one update control signal.

Abstract: A memory system includes physical memory devices or ranks of memory devices that can be set to reduced power modes. In one embodiment, a hardware memory controller receives memory instructions in terms of a logical address space. In response to the relative usages of different addresses within the logical address space, the memory controller maps the logical address space to physical memory in a way that reduces the number of memory devices that are being used. Other memory devices are then set to reduced power modes. In another embodiment, an operating system maintains a free page list indicating portions of physical memory that are not currently allocated. The operating system periodically sorts this list by group, where each group corresponds to a set or rank of memory devices. The groups are sorted in order from those receiving the heaviest usage to those receiving the lightest usage.

Abstract: Systems and methods for reducing heat flux in memory systems are described. In various embodiments, heat flux reductions are achieved by manipulating the device IDs of individual memory devices that comprise a memory module. Through the various described techniques, the per-face heat flux can be desirably reduced. Further, in some embodiments, reductions in heat flux are achieved by providing control lines that operably connect memory devices on different faces of a memory module.

Abstract: A memory controller controls access to, and the power state of a plurality of dynamic memory devices. A cache in the memory controller stores entries that indicate a current power state for a subset of the dynamic memory devices. Device state lookup logic responds to a memory access request by retrieving first information from an entry, if any, in the cache corresponding to a device address in the memory access request. The device state lookup logic generates a miss signal when the cache has no entry corresponding to the device address. It also retrieves second information indicating whether the cache is currently storing a maximum allowed number of entries for devices in a predefined mid-power state. Additional logic converts the first and second information and miss signal into at least one command selection signal and at least one update control signal. Cache update logic updates information stored in the cache in accordance with the at least one update control signal.