Sun Microsystems, Inc.

Tellabs San Jose, Inc.

Glenn Gracon

Michael Wasserman

Michael G Lavelle

David C Kehlet

David S Curry

Justin Michael Mahan

Kenneth C Hsu

Steven Te-Chun Yu

Murray Bowles

Nathaniel David Naegle

Michael W Schimpf

David Naegle

A packet scheduler includes a packet manager interface, a policer, a congestion manager, a scheduler, and a virtual output queue (VOQ) handler. The policer assigns a priority to each packet. Depending on congestion levels, the congestion manager determines whether to send a packet based on the packet's priority assigned by the policer. The scheduler schedules packets in accordance with configured rates for virtual connections and group shapers. A scheduled packet is queued at a virtual output queue (VOQ) by the VOQ handler. In one embodiment, the VOQ handler sends signals to a packet manager (through the packet manager interface) to instruct the packet manager to transmit packets in a scheduled order.

Apparatus and methods for scheduling packets in a broadband data stream

A signature capture and analysis system suitable for use in a high performance computer graphics system is described. The system employs a distributed network of signature analysis registers (SARs) which may be configured to capture and accumulate information from one or more channels of data over pre-defined periods of time. The SARs may be so distributed to allow for the isolation of faults to a sub-system level. The signature values developed in these SARs are, in some cases pre-seeded, and may include contributions from both data and control signals. Checking of the signature values against known good or expected outcomes is provided for. In some cases the SARs may be implemented as linear hybrid cellular automatons.

Signature analysis registers for testing a computer graphics system

A graphics system that is configured to synchronize a slave display channel to a master display channel may include a master display timing generator configured to provide a frame event indication and a slave display timing generator. The slave display timing generator may be configured to receive the frame event indication and, in response to receiving the frame event indication during its active display period, the slave display timing generator may be configured to wait until its current active display period ends and then jump to its synchronization point. Alternatively, the slave display timing generator may be configured to jump to its synchronization point immediately or after the end of the current horizontal line, and any remaining display information in an interrupted frame may be displayed during the next active display period.

Synchronizing multiple display channels

A graphics system that may be shared between multiple display channels includes a frame buffer, an arbiter, and two pixel output buffers. The arbiter arbitrates between the display channels' requests for display information from the frame buffer and forwards a selected request to the frame buffer. The frame buffer is divided into a first and a second portion. The arbiter alternates display channel requests for data between the first and second portions of the frame buffer. The frame buffer outputs display information in response to receiving the forwarded request, and pixels corresponding to this display information are stored in the output buffers. The arbiter selects which request to forward to the frame buffer based on a relative state of neediness of each of the requesting display channels.

Method and apparatus for reducing inefficiencies in shared memory devices

A graphics system that may be shared between multiple display channels includes a frame buffer, two arbiters, a pixel buffer, and several display output queues. The first arbiter arbitrates between the display channels' requests for display information from the frame buffer and forwards a selected request to the frame buffer. The frame buffer outputs display information in response to receiving the forwarded request, and pixels corresponding to this display information are stored in the pixel buffer. Each display channel has a corresponding display output queue that provides data to a display and generates a request for pixels from the pixel buffer. A pixel request arbiter receives the pixel requests generated by the display output queues, selects one of the pixel requests, and forwards the selected request to the pixel buffer. In response, the pixel buffer outputs pixels to the display output queue that generated the selected pixel request.

Growing community of inventors

Palo Alto, CA, United States of America

Glenn Gracon