Apple Inc.

Nachiappan Chidambaram Nachiappan

Vinodh R Cuppu

Jaideep Dastidar

Benjamin K Dodge

Shawn Munetoshi Fukami

Yiu Chun Tse

Matthew R Johnson

Ripudaman Singh

Deniz Balkan

Hengsheng Geng

David L Trawick

Systems, apparatuses, and methods for controlling bandwidth through shared transaction limits are described. An apparatus includes at least a plurality of agents, a plurality of transaction-limit (T-Limit) nodes, a T-Limit manager, and one or more endpoints. The T-Limit manager creates a plurality of credits for the plurality of agents to send transactions to a given endpoint. Then, the T-Limit manager partitions the credits into N+1 portions for N agents, wherein the extra N+1 portion is a shared pool for use by agents when they run out of their private credits. The T-Limit manager assigns a separate private portion of the N portions to the N agents for use by only the corresponding agent. When an agent runs out of private credits, the agent's T-Limit node sends a request to the T-Limit manager for credits from the shared pool.

Systems and methods to control bandwidth through shared transaction limits

A system and method for efficiently arbitrating traffic on a bus. A computing system includes a fabric for routing traffic among one or more agents and one or more endpoints. The fabric includes multiple arbiters in an arbitration hierarchy. Arbiters store traffic in buffers with each buffer associated with a particular traffic type and a source of the traffic. Arbiters maintain a respective urgency counter for keeping track of a period of time traffic of a particular type is blocked by upstream arbiters. When the block is removed, the traffic of the particular type has priority for selection based on the urgency counter. When arbiters receive feedback from downstream arbiters or sources, the arbiters adjust selection priority accordingly. For example, changes in bandwidth requirement, low latency tolerance and active status cause adjustments in selection priority of stored requests.

Systems and methods for arbitrating traffic in a bus

Systems, apparatuses, and methods for implementing a configurable packet arbiter with minimum progress guarantees are described. An arbiter includes at least control logic, a plurality of counters, and a tunables matrix. The tunables matrix stores values for a plurality of configurable parameters for the various transaction sources of the arbiter. These parameter values determine the settings that the arbiter uses for performing arbitration. One of the parameters is a minimum progress guarantee value that specifies how many times each source should be picked per interval. The minimum progress guarantee helps to reduce arbitration-related jitter. Also, the arbiter includes a grant counter for each source. After the minimum progress guarantees are satisfied, the arbiter selects the source with the lowest grant counter among the sources with packets eligible for arbitration. Then, the arbiter increments the grant counter of the winning source by a grant increment amount specific to the source.

Configurable packet arbitration with minimum progress guarantees

A system and method for efficiently allocating data storage to agents. A computing system includes an interconnect with intermediate buffers for storing transactions and corresponding payload data during transport between sources and destinations. A data storage limit is set on an amount of data storage corresponding to outstanding transactions for each of the multiple sources based on the initial buffer assignments. A number of outstanding transactions for each of the multiple sources is limited based on a corresponding data storage limit. If the rate of allocation of a given buffer assigned to a first source exceeds a threshold, then a second source is selected with available space exceeding a threshold in an assigned buffer. If it is determined the second source is not assigned to a buffer with a rate of allocation exceeding a threshold, then buffer storage is reassigned from the second source to the first source.

Systems and methods for providing a back pressure free interconnect

Growing community of inventors

Santa Clara, CA, United States of America

Nachiappan Chidambaram Nachiappan