US 12,591,525 B2Granted

Mechanisms for arbitrating among packets in hierarchical arbitration architecture

AssigneeApple Inc.

InventorsLital Levy-Rubin, Daniel U. Becker, Moti Altahan, Nabeel Achlaug, Rafael K. Vivas Maeda, Jeonghee Shin, Roi Uziel

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Abstract

In an embodiment, a computer system comprises one or more co-packaged integrated circuits having a communication fabric that couples various agent circuits. The agent circuits transmit packets via the communication fabric, which can include command-data packets and command packets. In various embodiments, the communication fabric includes an arbitration circuit to arbitrate among packets to transmit on the fabric. The command-data packets may be allocated to a first plurality of virtual channels while the command packets are allocated to a second plurality of virtual channels. The arbitration circuit may arbitrate among the first plurality of virtual channels to select a command-data packet and the second plurality of virtual channels to select a command packet. The arbitration circuit may then arbitrate between the selected command-data packet and the selected command packet to select a winning packet to transmit based on a history of previously selected packets.

Claims20

Dependent claims

An apparatus, comprising:

a plurality of agent circuits of a computer system that includes one or more co-packaged integrated circuits, wherein the plurality of agent circuits includes a memory controller circuit that is configured to couple to a memory;
and
a communication fabric that is coupled to ones of the plurality of agent circuits and includes a plurality of network interface circuits, wherein the agent circuits are configured to transmit, via the communication fabric, packets, including particular packets to read and write data with respect to the memory, and wherein a particular one of the plurality of network interface circuits includes:
a plurality of queues configured to store ones of the packets, including command-data packets and command packets, wherein a command-data packet includes a command and data, and a command packet includes a command without data, and wherein the command-data packets are allocated to a first plurality of virtual channels and the command packets are allocated to a second plurality of virtual channels;
and
an arbitration circuit configured to arbitrate among packets stored in the plurality of queues to transmit on the communication fabric, wherein the arbitration circuit is configured to:
arbitrate among the first plurality of virtual channels to select a command-data packet;
arbitrate among the second plurality of virtual channels to select a command packet;
and
arbitrate between the selected command-data packet and the selected command packet to select a winning packet to transmit based on a history of previously selected packets in a plurality of previous arbitration cycles.

7 more elements

A method, comprising:

arbitrating, by an arbitration circuit of an integrated circuit that comprises a plurality of agent circuits configured to transmit packets on a communication fabric of the integrated circuit, among a first set of queues storing command-data packets to select a command-data packet, wherein a given command-data packet includes a command and data;
arbitrating, by the arbitration circuit, among a second set of queues storing command packets to select a command packet, wherein a given command packet includes a command without data;
arbitrating, by the arbitration circuit, between the selected command-data packet and the selected command packet to select a winning packet based on a history of previously selected packets in a plurality of previous arbitration cycles;
and
transmitting, by the arbitration circuit, the winning packet on the communication fabric of the integrated circuit.

2 more elements

An integrated circuit, comprising:

a communication fabric;
and
at least one memory controller circuit coupled to the communication fabric and configured to couple to a memory;
and
a plurality of agent circuits coupled to the communication fabric and configured to transmit packets to read and write data with respect to the memory;
wherein the communication fabric includes:
a plurality of queues configured to store ones of the packets, including command-data packets and command packets, wherein a command-data packet includes a command and data, and a command packet includes a command without data;
and
an arbitration circuit configured to arbitrate among packets stored in the plurality of queues to transmit on the communication fabric, wherein the arbitration circuit includes first and second lower-level arbitration circuits that are coupled to a higher-level arbitration circuit,
wherein the first lower-level arbitration circuit is configured to arbitrate among the command-data packets to select a command-data packet,
wherein the second lower-level arbitration circuit is configured to arbitrate among the command packets to select a command packet, and
wherein the higher-level arbitration circuit is configured to arbitrate between the selected command-data packet and the selected command packet to select a winning packet to transmit based on a history of previously selected packets in a plurality of previous arbitration cycles.

9 more elements

Dependencies are inferred from the claim text.