Abstract: A design structure embodied in a machine readable storage medium for designing, manufacturing, and/or testing a design for scheduling the servicing of data requests, using the variable latency mode, in an FBDIMM memory sub-system is provided. A scheduling algorithm pre-computes return time data for data connected to DRAM buffer chips and stores the return time data in a table. The return time data is expressed as data return time binary vectors with one bit equal to “1” in each vector. For each received data request, the memory controller retrieves the appropriate return time vector. Additionally, the scheduling algorithm utilizes an updated history vector to determine whether the received request presents a conflict to the executing requests. By computing and utilizing a score for each request, the scheduling algorithm re-orders and schedules the execution of selected requests to preserve as much data bus bandwidth as possible, while avoiding conflict.

Abstract: A memory subsystem includes Data Store 0 and Data Store 1. Each data store is partitioned into N buffers, N>1. An increment of memory is formed by a buffer pair, with each buffer of the buffer pair being in a different data store. Two buffer pair formats are used in forming memory increments. A first format selects a first buffer from Data Store 0 and a second buffer from Data Store 1, while a second format selects a first buffer from Data Store 1 and a second buffer from Data Store 0. A controller selects a buffer pair for storing data based upon the configuration of data in a delivery mechanism, such as switch cell.

Abstract: A design structure embodied in a machine readable storage medium for designing, manufacturing, and/or testing a design is provided. The design structure generally includes a computer system that includes a CPU, a memory controller, memory, a bus connecting the CPU, memory controller and memory, circuitry for providing a speculative read threshold corresponding to a selected percentage of the total number of reads that can be speculatively issued, and circuitry for intermixing demand reads and speculative reads in accordance with the speculative read threshold.

Abstract: A two-level error control protocol detects errors on the subline level and corrects errors using the codeword for the entire line. This enables a system to read small pieces of coded data and check for errors before accepting them, and in case errors are detected, the whole codeword is read for error correction.

Abstract: A system to improve miscorrection rates in error control code may include an error control decoder with a safe decoding mode that processes at least two data packets. The system may also include a buffer to receive the processed at least two data packets from the error control decoder. The error control decoder may apply a logic OR operation to the uncorrectable error signal related to the processing of the at least two data packets to produce a global uncorrectable error signal. The system may further include a recipient to receive the at least two data packets and the global uncorrectable error signal.

Abstract: A system to improve error correction may include a fast decoder to process data packets until the fast decoder finds an uncorrectable error in a data packet at which point a request for at least two data packets is generated. The system may also include a slow decoder to possibly correct the uncorrectable error in a data packet based upon the at least two data packets.

Abstract: A system to improve error code decoding with retries may include a processing unit that requests data packets, and a queue to hold the data packets for the processing unit. The system may also include a decoder to determine a processing time for each data packet in the queue based upon any errors in each data packet, and if the processing time for a particular data packet is greater than a threshold, then to renew any requests for the data packets that are in the queue.

Abstract: Systems, methods and media for selectively closing pages in a memory in anticipation of a context switch are disclosed. In one embodiment, a table is provided to keep track of open pages for different processes. The table comprises rows corresponding to banks of memory and columns corresponding to cores of a multi-core processing system. When a context switch signal is received, the system unsets a bit in a column corresponding to the core from which the process is to be context-switched out. If no other process is using a page opened by the process the page is closed.

Abstract: A method and system for scheduling the servicing of data requests, using the variable latency mode, in an FBDIMM memory sub-system. A scheduling algorithm pre-computes return time data for data connected to all DRAM buffer chips and stores the return time data in a table. The return time data is expressed as a set of data return time binary vectors with one bit equal to “1” in each vector. For each received data request, the memory controller retrieves the appropriate return time vector. Additionally, the scheduling algorithm utilizes an updated history vector representing a compilation of data return time vectors of all executing requests to determine whether the received request presents a conflict to the executing requests. By computing and utilizing a score for each request, the scheduling algorithm re-orders and schedules the execution of selected requests to preserve as much data bus bandwidth as possible, while avoiding conflict.

Abstract: Methods and system for reducing latency associated with a read operation in a processor memory system are provided. In one implementation, the method includes receiving an early indicator corresponding to read data from a memory, delaying the early indicator in accordance with a pre-determined delay such that the early read indicator is passed to a bus in advance of the read data; and dynamically adjusting the pre-determined delay using an adjustment delay circuit, the pre-determined delay being adjusted responsive to a change in operational speed of the bus or change in operational speed of a processor coupled to the bus.

Abstract: Systems and methods for providing automatic read flow control in a cascade interconnect memory system. A hub device includes an interface to a channel in a cascade interconnect memory system for connecting the hub device to an upstream hub device or a memory controller. The channel includes an upstream bus and a downstream bus. The hub device also includes read data flow control logic for determining when to transmit data on the upstream bus. The determining is responsive to an order of commands received on the downstream bus and to current traffic on the upstream bus.

Abstract: Systems and methods for providing a variable frame format protocol in a cascade interconnected memory system. The systems include a memory hub device that utilizes a first bus interface to communicate on a high-speed bus. The hub device also includes frame decode logic for translating variable format frames received via the first bus interface into memory device commands and data. The translating includes identifying write data headers and associated write data for self-registering write to data buffer commands.

Abstract: A memory buffer, memory system and method for power-on initialization and test for a cascade interconnect memory system. The memory buffer includes a bus interface to links in a high-speed channel for communicating with a memory controller via a direct connection or via a cascade interconnection through an other memory buffer. The interface is operable in a SBC mode and a high-speed mode. The memory buffer also includes a field service interface (FSI) slave for receiving FSI signals from a FSI master. In addition, the memory buffer includes logic for executing a power-on and initialization training sequence initiated by the memory controller.

Abstract: A communication interface device, system, method, and design structure for enhancing bus efficiency and utilization in a memory system. The communication interface device includes a first bus interface to communicate on a high-speed bus, a second bus interface to communicate on a lower-speed bus, and clock ratio logic configurable to support multiple clock ratios between the high-speed bus and the lower-speed bus. The clock ratio logic reduces a high-speed clock frequency received at the first bus interface and outputs a reduced ratio of the high-speed clock frequency on the lower-speed bus via the second bus interface supporting variable frame sizes.

Abstract: A hub device, memory system, and method for providing a cascade interconnect memory system with enhanced reliability. The hub device includes an interface to a high-speed bus for communicating with a memory controller. The memory controller and the hub device are included in a cascade interconnect memory system and the high-speed bus includes bit lanes and one or more clock lanes. The hub device also includes a bi-directional fault signal line in communication with the memory controller and readable by a service interface. The hub device also includes a fault isolation register (FIR) for storing information about failures detected at the hub device, the information including severity levels of the detected failures. In addition, the hub device includes error recovery logic for responding to a failure detected at the hub device. Responding to the error includes recording a severity level of the failure in the FIR and taking an action at the hub device that is responsive to the severity level of the failure.

Abstract: A communication interface device, system, method, and design structure for error correcting code (ECC) protected quasi-static bit communication (SBC) on a high-speed bus are provided. The communication interface device includes high-speed sampling logic to capture high-speed data from the high-speed bus using a high-speed sampling clock and SBC sampling logic to capture SBC samples from the high-speed bus using an SBC sampling clock. The SBC sampling clock is slower than the high-speed sampling clock. The communication interface device also includes an SBC finite state machine (FSM) to detect a received SBC command in response to a static pattern persisting for a predetermined number of the SBC samples and command decoding logic to decode the received SBC command.

Abstract: In one embodiment, a method is disclosed for timing responses to a plurality of memory requests. The method can include sending a plurality of memory requests to a plurality of in-line memory modules. The requests can be sent over a channel from a plurality of channels, where each channel can have a plurality of lanes. The method can receive responses to the plurality of memory requests over the channel and monitor the response to detect a timing relationship between at least two lanes from the plurality of lanes. In addition, the method can adjust a timing of a register loading and unloading sequence in response to the monitoring of multiple lanes and channels. Other embodiments are also disclosed.

Abstract: Methods, systems, and computer program products are provided for dynamic selective memory mirroring in solid state devices. An amount of memory is reserved. Sections of the memory to select for mirroring in the reserved memory are dynamically determined. The selected sections of the memory contain critical areas. The selected sections of the memory are mirrored in the reserved memory.

Abstract: A design structure embodied in a machine readable storage medium for designing, manufacturing, and/or testing a design is provided. The design structure generally includes a computer system that includes a CPU, a storage device, circuitry for providing a speculative access threshold corresponding to a selected percentage of the total number of accesses to the storage device that can be speculatively issued, and circuitry for intermixing demand accesses and speculative accesses in accordance with the speculative access threshold.

Abstract: A design structure embodied in a machine readable storage medium for designing, manufacturing, and/or testing a design is provided. The design structure generally includes a computer system that includes a CPU, a memory controller, memory, a bus connecting the CPU, memory controller and memory, circuitry for providing a speculative read threshold corresponding to a selected percentage of the total number of reads that can be speculatively issued, and circuitry for intermixing demand reads and speculative reads in accordance with the speculative read threshold.