Sun Microsystems, Inc.

Intel Corporation

Oracle International Corporation

Oracle America, Inc.

Brian McGee

Kevin B Normoyle

Karthikeyan Avudaiyappan

Rajasekhar Cherabuddi

Robert Cypher

Ashley N Saulsbury

Ricky C Hetherington

Anup K Sharma

Jurgen M Schulz

Haakan E Zeffer

David M Kahn

Wayne F Seltzer

Bharat K Daga

Meera Kasinathan

Bruce J Chang

Vishak Chandrasekhar

Sutikshan Bhutani

Jade B Chau

Methods for invasive debug of a processor without processor execution of instructions are disclosed. As a part of a method, a memory mapped I/O of the processor is accessed using a debug bus and an operation is initiated that causes a debug port to gain access to registers of the processor using the memory mapped I/O. The invasive debug of the processor is executed from the debug port via registers of the processor.

Systems and methods for invasive debug of a processor without processor execution of instructions

The disclosed embodiments disclose techniques for performing physical domain error isolation and recovery in a multi-domain system, where the multi-domain system includes two or more processor chips and one or more switch chips that provide connectivity and cache-coherency support for the processor chips, and the processor chips are divided into two or more distinct domains. During operation, one of the switch chips determines a fault in the multi-domain system. The switch chip determines an originating domain that is associated with the fault, and then signals the fault and an identifier for the originating domain to its internal units, some of which perform clearing operations that clear out all traffic for the originating domain without affecting the other domains of the multi-domain system.

Physical domain error isolation and recovery in a multi-domain system

Some embodiments of the present invention provide a system that processes a request for a cache line in a multiprocessor system that supports a directory-based cache-coherence scheme. During operation, the system receives the request for the cache line from a requesting node at a home node, wherein the home node maintains directory information for all or a subset of the address space which includes the cache line. Next, the system performs an action at the home node, which causes a valid copy of the cache line to be sent to the requesting node. The system then completes processing of the request at the home node without waiting for an acknowledgment indicating that the requesting node received the valid copy of the cache line.

Bandwidth-efficient directory-based coherence protocol

A processor employing device-specific memory address translation. In one embodiment, a processor may include a device interface configured to receive a memory access request from an input/output (I/O) device, where the request specifies a virtual memory address and a first requestor identifier (ID) that identifies the I/O device. The processor may also include an I/O memory management unit coupled to the device interface and configured to determine whether a virtual-to-physical memory address translation corresponding to the virtual memory address is stored within an I/O memory translation buffer. The I/O memory management unit may be further configured to determine whether a second requestor ID stored within the I/O memory translation buffer and corresponding to the memory address translation matches the first requestor ID. If the first and second requestor IDs do not match, the I/O memory management unit may disallow the memory access request and to signal an error condition.

Processor and method for device-specific memory address translation

In one of the many embodiments disclosed herein, a method for dispatching read and write requests to a memory is disclosed which includes queuing at least one write request in a write queue and queuing an incoming read request in a read queue. The method also includes comparing the read request with at least one write request in the write queue to detect a matching write request, and if there is a matching write request, storing a write queue index of the matching write request as a first entry in an ordering queue. The method further includes dispatching the at least one write request to the memory in response to the first ordering queue entry.

Memory controller and method using read and write queues and an ordering queue for dispatching read and write memory requests out of order to reduce memory latency

A memory controller for a memory subsystem of a computer system connects to a processor bus. The memory controller is for use with memory devices such as RDRAM or DDR SDRAM that allow for multiple open pages. Memory references are remapped by an address mapper and processed by a page tracking buffer to keep track of open pages in the memory devices. The controller also has a state machine, and an interface to memory devices. The page tracking buffer has a row address content addressable memory for determining when a reference is in an open page, and a bank content addressable memory for determining when a reference is to the same bank as an open page. The controller closes open pages of a bank prior to opening new pages in that bank. The page tracking buffer has fewer lines than the product of the maximum number of memory devices times the maximum number of simultaneously open pages of each device, but provides for tracking any page of any of the memory devices.

System and method for using a page tracking buffer to reduce main memory latency in a computer system

A multiprocessor system includes a plurality of central processing units (CPUs) connected to one another by a system bus. Each CPU includes a cache controller to communicate with its cache, and a primary memory controller to communicate with its primary memory. When there is a cache miss in a CPU, the cache controller routes an address request for primary memory directly to the primary memory via the CPU as a speculative request without access the system bus, and also issues the address request to the system bus to facilitate data coherency. The speculative request is queued in the primary memory controller, which in turn retrieves speculative data from a specified primary memory address. The CPU monitors the system bus for a subsequent transaction that requests the specified data in the primary memory. If the subsequent transaction requesting the specified data is a read transaction that corresponds to the speculative address request, the speculative request is validated and becomes non-speculative. If, on the other hand, the subsequent transaction requesting the specified data is a write transaction, the speculative request is canceled.

Method to reduce memory latencies by performing two levels of speculation

Growing community of inventors

San Jose, CA, United States of America

Brian McGee