Abstract: An apparatus and method for prefetching cache data in response to data requests. The prefetching uses the memory addresses of requested data to search for other data, from a related address, in a cache. This, or other data, may then be prefetched based on the result of the search.

Abstract: A combination of techniques to prevent deadlocks and livelocks in a computer system having a dispatcher and multiple downstream command queues. In one embodiment, a broadcast transaction that requires simultaneously available space in all the affected downstream command queues becomes a delayed transaction, so that the command queues are reserved and other transactions are retried until the broadcast transaction is completed. In another embodiment, a bail-out timer is used to defer a transaction if the transaction does not complete within a predetermined time. In yet another embodiment, a locked transaction that potentially addresses memory space controlled by a programmable attribute map is handled as a delayed transaction if there is less than a predetermined amount of downstream buffer space available for the transaction.

Abstract: A write cache that reduces the number of memory accesses required to write data to main memory. When a memory write request is executed, the request not only updates the relevant location in cache memory, but the request is also directed to updating the corresponding location in main memory. A separate write cache is dedicated to temporarily holding multiple write requests so that they can be organized for more efficient transmission to memory in burst transfers. In one embodiment, all writes within a predefined range of addresses can be written to memory as a group. In another embodiment, entries are held in the write cache until a minimum number of entries are available for writing to memory, and a least-recently-used mechanism can be used to decide which entries to transmit first. In yet another embodiment, partial writes are merged into a single cache line, to be written to memory in a single burst transmission.

Abstract: A write cache that reduces the number of memory accesses required to write data to main memory. When a memory write request is executed, the request not only updates the relevant location in cache memory, but the request is also directed to updating the corresponding location in main memory. A separate write cache is dedicated to temporarily holding multiple write requests so that they can be organized for more efficient transmission to memory in burst transfers. In one embodiment, all writes within a predefined range of addresses can be written to memory as a group. In another embodiment, entries are held in the write cache until a minimum number of entries are available for writing to memory, and a least-recently-used mechanism can be used to decide which entries to transmit first. In yet another embodiment, partial writes are merged into a single cache line, to be written to memory in a single burst transmission.

Abstract: An apparatus and method for prefetching cache data in response to data requests. The prefetching uses the memory addresses of requested data to search for other data, from a related address, in a cache. This, or other data, may then be prefetched based on the result of the search.

Abstract: A computer system that includes at least two host agents is provided. The computer system further includes a chipset that includes a resource to be shared by the at least two host agents. The chipset is coupled to the at least two host agents. The chipset prevents a first host agent, that occupies the shared resource to access the shared resource until a second host agent, has made progress in accessing said shared resource.

Abstract: A technique to reduce accumulated latencies in bus transmission time when a bus inversion scheme is employed. The bus inversion scheme inverts all the data bits whenever more than one-half of the data bits are active, so that the bus never has more that one-half of the bits active during a data transfer. This minimizes the number of driver circuits that are actively driving the bus at any given time. Since it takes a certain amount to time to determine if more than one-half of the bits are active, this process can add to overall latency, or data transfer time on the bus. By placing the bus inversion function in parallel with another function that also contributes to bus latency, such as error correction code (ECC) calculation, only the more time-consuming of the two functions will increase bus latency.

Abstract: A system is described for prefetching data from a main memory before the data is requested by a processor. The system includes a prefetch buffer having a number of entries to store prefetch reads. Each entry in the prefetch buffer includes a storage area designated for data and address. The system also includes a number of state machines, each state machine to track data phase for each entry in the prefetch buffer. A read request controller is coupled to the prefetch buffer and is configured to receive a read request from the processor or I/O devices and controls dispatching of prefetch requests to a main memory.

Abstract: A computer system that includes at least two host agents is provided. The computer system further includes a chipset that includes a resource to be shared by the at least two host agents. The chipset is coupled to the-at least two host agents. The chipset prevents a first host agent, that occupies the shared resource to access the shared resource until a second host agent, has made progress in accessing said shared resource.

Abstract: A system is described for servicing a full cache line in response to a partial cache line request. The system includes a storage to store at least one cache line, a hit/miss detector, and a data mover. The hit/miss detector receives a partial cache line read request from a requesting agent and dispatches a fetch request to a memory device to fetch a full cache line data that contains data requested in the partial cache line read request from the requesting agent. The data mover loads the storage with the full cache line data returned from the memory device and forwards a portion of the full cache line data requested by the requesting agent. If data specified in a subsequent partial cache line request from the requesting agent is contained within the full cache line data specified in the previously dispatched fetch request, the hit/miss detector will send a command to the data mover to forward another portion of the full cache line data stored in the storage to the requesting agent.

Abstract: A method for controlling device temperature. The method involves determining access rate to a component, comparing the access rate with a predetermined threshold modified by a weighted value and controlling the temperature of the component through corrective action.

Abstract: A system is described for servicing a full cache line in response to a partial cache line request. The system includes a storage to store at least one cache line, a hit/miss detector, and a data mover. The hit/miss detector receives a partial cache line read request from a requesting agent and dispatches a fetch request to a memory device to fetch a full cache line data that contains data requested in the partial cache line read request from the requesting agent. The data mover loads the storage with the full cache line data returned from the memory device and forwards a portion of the full cache line data requested by the requesting agent. If data specified in a subsequent partial cache line request from the requesting agent is contained within the full cache line data specified in the previously dispatched fetch request, the hit/miss detector will send a command to the data mover to forward another portion of the full cache line data stored in the storage to the requesting agent.

Abstract: A computer system that includes a host processor (HP), a system memory (SM), and a host bridge coupled to the HP and SM is provided. The host bridge asserts a first read request to the SM and, prior to availability of snoop results in connection with the first read request, the host bridge asserts a following second read request to the SM.

Abstract: According to one embodiment, the present invention discloses a computer system that includes a memory and a memory controller. The memory controller includes a refresh timing circuit that generates clock pulses. The clock pulses are used to trigger memory refresh events. According to a further embodiment, the refresh timing circuit includes a clock generator, a counter coupled to the clock generator and a storage register coupled to the clock generator and counter. Further, the refresh timing circuit includes a comparator coupled to the clock generator, the counter and the storage register.

Abstract: A computer system is provided. The computer system includes a host processor (HP), a system memory (SM), and an input/output (I/O) master device to perform a read of a continuous stream of data to the SM. The computer system also includes a bridge coupled to the HP, SM, and I/O master device. The bridge reads ahead to the SM when the I/O master device reads a continuous stream of data from the SM. The bridge aborts read ahead accesses to the SM, prior to an access commit point to the SM, responsive to disengagement of the I/O master device.

Abstract: According to one embodiment, a computer system is disclosed. The computer system includes a processor, a memory, an inverting device, a storage device coupled to the inverting device and a device coupled to the storage device. The device receives byte enable information and inverted information and provides inverted byte enable information to the memory upon a write back operation to the memory.

Abstract: In a bus resource having an outbound pipe for processing both non-posted and posted transactions in a FIFO manner, a rejected non-posted transaction at the head of the outbound pipe is moved aside and into an auxiliary buffer to avoid a potential blockage of the outbound pipe. The auxiliary buffer is for holding transaction information and return data of the rejected non-posted transaction. The rejected transaction is eventually completed from the auxiliary buffer as determined by an arbiter.

Abstract: An arbiter comprising logic circuitry configured to delay granting bus ownership to an agent X in response to receiving a first signal which indicates that a device coupled to the bus is not available to service transactions directed at the device over the bus. For instance, the device may be a bridge and the grant is delayed if an inbound pipe of the bridge is full. The arbiter may provide a borrowed grant to an outbound pipe of the device for performing a transaction on the bus while waiting for an inbound pipe of the device to become available.

Abstract: According to one embodiment, the present invention discloses a method of accessing a memory in a computer system. The method includes granting access of the memory to a first agent after arbitration. Next, the first agent relinquishes control of the memory. Subsequently, a request is received from a second agent during arbitration to access the memory. It is next determined whether the second agent has a higher priority request classification than the first agent. If the second agent does not have a higher priority request classification than the first agent, it is determined whether a predetermined time interval has elapsed since the first agent relinquished control of the memory. If the predetermined time interval has not elapsed, access of the memory is withheld from the second agent. According to a further embodiment, access to the memory is granted if it is determined that the predetermined time interval has elapsed.

Abstract: An embodiment of the invention is directed at a bridge having an outbound pipe for buffering transaction information and data being transported from various devices to a bus. The bridge has an arbiter for granting requests associated with these devices to access the outbound pipe for transferring the transaction information and data into the pipe. The bridge generates a reject signal in response to an initial request associated with an initial transaction from a first one of the devices if the outbound pipe is unavailable to accept further transaction information or data. The bridge has response control logic for generating a retry response for the initial transaction in response to the reject signal. The bridge is able to assert a stamp signal in response to the reject signal. The arbiter in response to the stamp being asserted waits, without granting any other lower priority requests to access the outbound pipe, until a subsequent transaction from the first device makes progress.