Abstract: Multiple interfaces dedicated to individual logic circuits such as memory arrays are capable of being dynamically reconfigured from operating separately and in parallel to operating in a more collective manner to ensure that data associated with all of the logic circuits will be communicated irrespective of a failure in any of the interfaces. Specifically, a plurality of interfaces, each of which being ordinarily configured to communicate data associated with an associated logic circuit in parallel with the other interfaces, may be dynamically reconfigured, e.g., in response to a detected failure in one or more of the interfaces, to communicate data associated with each of the interfaces over each of at least a subset of the interfaces in a time multiplexed and replicated manner.

Abstract: A method and apparatus implement cache coherency and reduced latency using multiple controllers for a memory system, and a design structure is provided on which the subject circuit resides. A first memory controller uses a first memory as its primary address space, for storage and fetches. A second memory controller is also connected to the first memory. A second memory controller uses a second memory as its primary address space, for storage and fetches. The first memory controller is also connected to the second memory. The first memory controller and the second memory controller, for example, are connected together by a processor communications bus. A request and send sequence of the invention sends data directly to a requesting memory controller eliminating the need to re-route data back through a responding controller, and improving the latency of the data transfer.

Abstract: A method and apparatus implement redundant memory access using multiple controllers for a memory system, and a design structure on which the subject circuit resides are provided. A first memory controller uses a first memory and a second memory controller uses the second memory as its respective primary address space, for storage and fetches. The second memory controller is also connected to the first memory. The first memory controller is also connected to the second memory. The first memory controller and the second memory controller, for example, are connected together by a processor communications bus. When one of the first memory controller or the second memory controller fails, then the other memory controller is notified. The other memory controller takes control of the memory for the failed controller, using the direct connection to that memory, and maintains coherence of both the first memory and second memory.

Abstract: A memory chip having a data bus having a plurality of bits. The number of bits is apportioned between a read portion and a write portion. The write portion is dedicated to receiving data that is to be written into an array on the memory chip; the read portion is dedicated to driving data that has been read from the array on the memory chip. The apportionment is programmable. Apportionment can be specified by programming signal pins on the memory chip, connecting the signal pins to appropriate logical values. The apportionment can alternatively be specified by scanning apportionment information into the memory chip at bring up time. The apportionment and also alternatively be specified by receiving apportionment information in an address/command word.

Abstract: A computer system having patrol snoop sequencer that sequences through addresses of cache lines held in a higher level cache, making snoop reads using those addresses to a lower level cache. If a particular cache line held in the higher level cache is not held in the lower level cache, the particular cache line is identified as an eviction candidate in the higher level cache when a new cache line must be loaded into the higher level cache.

Abstract: A diagnostic interface architecture for a memory device supports in one aspect one or more dynamically reconfigurable functional interconnects normally utilized in connection with reading data from the memory device and/or writing data to the memory device. The dynamically reconfigurable functional interconnects are capable of being configured to operate in either functional or diagnostic modes, whereby in the diagnostic mode, such interconnects may be used to communicate diagnostic information to support one or more diagnostic operations. The diagnostic interface architecture may also support multiple diagnostic interfaces in a given memory device, with at least one such diagnostic interface being capable of being selectively enabled in response to a failure in another diagnostic interface.

Abstract: The present invention implements a mechanism to decide when it is beneficial to switch from the current virtual input/output mechanism to a different one. The present invention determines which input/output mechanism each virtual machine should use based on the available input/output resources of the virtual machines (with their respective available input/output adapters), the number of virtual machines running and their input/output needs, and the input/output needs of the virtual machine being considered. The present invention also provides a mechanism for virtual machine to seamlessly switch input/output mechanisms. When beneficial, the standard hot-plug mechanism of the virtual machine and the hypervisor is used to first remove the existing input/output mechanism and then add the new input/output mechanism.

Abstract: A self timed memory chip having an apportionable data bus. Access timing to an array on the memory chip is dynamically determined by circuitry on the memory chip. A ring oscillator on the memory chip has a frequency that is indicative of how fast an array on the memory chip can be accessed. The ring oscillator includes a bit line that is periodically charged and a memory element that subsequently discharges the bit line. The memory chip has a data bus interface having a number of bits. The data bus interface has a first number of bits apportioned to write data and a second number of bits apportioned to read data. The first number of bits and the second number of bits is programmable.

Abstract: A memory controller provides page copy logic that assures data coherency when a DMA operation to a page occurs during the copying of the page by the memory controller. The page copy logic compares the page index of the DMA operation to a copy address pointer that indicates the location currently being copied. If the page index of the DMA operation is less than the copy address pointer, the portion of the page that would be written to by the DMA operation has already been copied, so the DMA operation is performed to the physical address of the new page. If the page index of the DMA operation is greater than the copy address pointer, the portion of the page that would be written to by the DMA operation has not yet been copied, so the DMA operation is performed to the physical address of the old page.

Abstract: A diagnostic interface architecture for a memory device supports in one aspect one or more dynamically reconfigurable functional interconnects normally utilized in connection with reading data from the memory device and/or writing data to the memory device. The dynamically reconfigurable functional interconnects are capable of being configured to operate in either functional or diagnostic modes, whereby in the diagnostic mode, such interconnects may be used to communicate diagnostic information to support one or more diagnostic operations. The diagnostic interface architecture may also support multiple diagnostic interfaces in a given memory device, with at least one such diagnostic interface being capable of being selectively enabled in response to a failure in another diagnostic interface.

Abstract: Multiple interfaces dedicated to individual logic circuits such as memory arrays are capable of being dynamically reconfigured from operating separately and in parallel to operating in a more collective manner to ensure that data associated with all of the logic circuits will be communicated irrespective of a failure in any of the interfaces. Specifically, a plurality of interfaces, each of which being ordinarily configured to communicate data associated with an associated logic circuit in parallel with the other interfaces, may be dynamically reconfigured, e.g., in response to a detected failure in one or more of the interfaces, to communicate data associated with each of the interfaces over each of at least a subset of the interfaces in a time multiplexed and replicated manner.

Abstract: A memory system having a memory controller and a daisy chain of memory chips. The memory controller is coupled to memory chips in the daisy chain of memory chips by an address/command bus chain. The memory controller is coupled to memory chips in the daisy chain of memory chips by a data bus chain having a number of data bus bits. The data bus chain has a first portion of data bus bits dedicated to transmitting write data from the memory controller to a memory chip. The data bus chain has a second portion of data bus bits dedicated to transmitting read data from a memory chip to the memory controller. Apportionment of data bus bits between the first portion and the second portion is programmable. Programming is done by pin connection, scanning of a value, or by request from a processor coupled to the memory controller.

Abstract: A memory module contains a first interface for receiving data access commands and a second interface for re-transmitting data access commands to other memory modules, the second interface propagating multiple copies of received data access commands to multiple other memory modules. The memory module is preferably used in a high-capacity memory subsystem organized in a tree configuration in which data accesses are interleaved.

Abstract: A high-capacity memory subsystem architecture utilizes multiple memory modules arranged in a hierarchical tree configuration, in which at least some communications from an external source traverse successive levels of the tree to reach memory modules at the lowest level.

Abstract: A memory module contains an interface for receiving memory access commands from an external source, in which a first portion of the interface receives memory access data at a first bus frequency and a second portion of the interface receives memory access data at a second different bus frequency. Preferably, the memory module contains a second interface for re-transmitting memory access data, also operating at dual frequency. The memory module is preferably used in a high-capacity memory subsystem organized in a tree configuration in which data accesses are interleaved. Preferably, the memory module has multiple-mode operation, one of which supports dual-speed buses for receiving and re-transmitting different parts of data access commands, and another of which supports conventional daisy-chaining.

Abstract: A dual-mode memory chip supports a first operation mode in which received data access commands contain chip select data to identify the chip addressed by the command, and control logic in the memory chip determines whether the command is addressed to the chip, and a second operation mode in which the received data access command addresses a set of multiple chips. Preferably, the first mode supports a daisy-chained configuration of memory chips. Preferably the second mode supports a hierarchical interleaved memory subsystem, in which each addressable set of chips is configured as a tree, command and write data being propagated down the tree, the number of chips increasing at each succeeding level of the tree.

Abstract: A high-capacity memory subsystem architecture utilizes multiple memory modules arranged in one or more clusters, each attached to a respective hub which in turn is attached to a memory controller. Within a cluster, data is interleaved so that each data access command accesses all modules of the cluster. The hub communicates with the memory modules at a lower bus frequency, but the distributing of data among multiple modules enables the cluster to maintain the composite data rate of the memory-controller-to-hub bus.

Abstract: A high-capacity memory subsystem architecture utilizes multiple memory modules arranged in one or more clusters, each attached to a respective hub which in turn is attached to a memory controller. Within a cluster, data is interleaved so that each data access command accesses all modules of the cluster. The hub communicates with the memory modules at a lower bus frequency, but the distributing of data among multiple modules enables the cluster to maintain the composite data rate of the memory-controller-to-hub bus.

Abstract: A high-capacity memory subsystem architecture utilizes multiple memory modules coupled to one or more access modules by a communications medium, in which at least some data is transferred between an access module and memory modules at a first bus frequency, and at least some data is transferred between the access module and memory modules at a second bus frequency different from the first. Preferably, data is interleaved to reduce the required bus speed for read/write data, and the higher bus frequency is used to transfer command/address data. Preferably, the memory system employs memory chips having dual-mode operation, one of which supports a dual-speed bus.

Abstract: Multiple interfaces dedicated to individual logic circuits such as memory arrays are capable of being dynamically reconfigured from operating separately and in parallel to operating in a more collective manner to ensure that data associated with all of the logic circuits will be communicated irrespective of a failure in any of the interfaces. Specifically, a plurality of interfaces, each of which being ordinarily configured to communicate data associated with an associated logic circuit in parallel with the other interfaces, may be dynamically reconfigured, e.g., in response to a detected failure in one or more of the interfaces, to communicate data associated with each of the interfaces over each of at least a subset of the interfaces in a time multiplexed and replicated manner.