Browse Prior Art Database

Configurable Multi-Requester Lockout Mechanism for Transmit Queue Arbiter

IP.com Disclosure Number: IPCOM000012920D
Original Publication Date: 2003-Jun-10
Included in the Prior Art Database: 2003-Jun-10
Document File: 3 page(s) / 56K

Publishing Venue

IBM

Abstract

This mechanism details a way to handle various requesters on a transmit queue. It arbitrates between the various requestors that occur and is able to be configured to lockout certain requestors from the queue. The mechanism basically picks which requester has the highest priority and is not currently locked out, to be picked. Based on the configuration that the arbiter currently is operating on. This mechanism is especially useful when dealing with network processors that support various types of traffic. It allows for prioritization of on going traffic and new traffic coming into, in this case a pipeline.

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Configurable Multi-Requester Lockout Mechanism for Transmit Queue Arbiter

   This disclosure describes a lockout mechanism for an arbiter that is used with a common pipeline structure that processes transmit requests from transmit queues. The queues may contain both Ethernet* and asynchronous transfer mode (ATM) traffic, and is a configurable number of queues that can present transmit requests to a given single Ethernet or ATM port. This has several requirements.

For Ethernet: - When the port is idle and there are pipeline resources available to transmit the data, the queues must be processed in priority order - When the port is idle and there are insufficient pipeline resources available to transmit the data, all queues associated with this port must be disabled. - When a port is busy actively transmitting, all queues associated with this port must be disabled.

For ATM - When there are insufficient pipeline resources available all associated queues must be disabled.

The lockout mechanism uses a series of masks to apply locks to groups of transmit queues before they are presented to the transmit request arbiter. For a given port, a mask is turned on if the resources or pipeline stages needed to transmit the data are not available. The masks are expanded by configuration parameters and applied to all queues associated with that port. If a mask for a queue is on, that queue will not be serviced.

The following is a diagram of this structure

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The transmit section consists of two pipelines followed by a data buffer. An Ethernet frame or ATM cell transmit is started when a trans...