Reservation mechanism for nodes with phase constraints

A computer-implemented method of managing reservations between a plurality of processing nodes with phase-based arbitration constraints, where each processing node of the plurality of processing nodes includes an arbiter, the computer-implemented method comprising:

• requesting, by a source processing node of the plurality of processing nodes to an arbiter of the source processing node, transmission of a message from the source processing node of the plurality of processing nodes to a destination processing node of the plurality of processing nodes,
• wherein the source processing node and the destination processing node are connected within a circular topology network, wherein the circular topology network comprises a plurality of buses, wherein each bus of the plurality of buses provides a plurality of slots for transmission of information,
• wherein processing nodes of the plurality of processing nodes are configured with the phase-based arbitration constraints which regulate transmission of information on the plurality of buses to the destination processing node only on a cycle that matches a phase window in which the destination processing node is allowed to receive the information on the plurality of buses;
• determining, by the arbiter in the source processing node, that the source processing node has met a starvation condition when requesting transmission of the message, wherein the starvation condition is a predetermined amount of time the source processing node is unable to transmit a message,
• wherein a reservation policy for transmitting information on a communication bus of the plurality of buses according to the phase-based arbitration constraints is applied to the plurality of processing nodes when a processing node satisfies the starvation condition, the reservation policy defining a reservation window having a number of cycles that is determined in part by a most restrictive phase constraint of a processing node in the plurality of processing nodes, and the reservation policy resets at an end of the reservation window;
• placing, by the source processing node, a reservation for a given phase in a phase window onto a reservation bus of the plurality of buses, wherein the reservation adheres to the reservation policy restricting reservations between the plurality of processing nodes on the network, wherein the reservation is placed in a reserved slot allowed by the phase-based arbitration constraints of the destination processing node;
• observing, by the source processing node, a return corresponding to the reservation on the reservation bus providing the reserved slot for the message on the communication bus of the plurality of buses;
• and
• transmitting, by the source processing node, the message to the destination processing node in the reserved slot generated by the reservation.

A computer program product including at least one computer readable storage medium having computer executable instructions for managing reservations between a plurality of processing nodes with phase-based arbitration constraints, where each processing node includes an arbiter, that when executed by at least one computer cause the at least one computer to execute the instructions to:

• requesting, by a source processing node of a plurality of processing nodes to an arbiter of the source processing node, transmission of a message from the source processing node of the plurality of processing nodes to a destination processing node of the plurality of processing nodes,
• wherein the source processing node and the destination processing node are connected within a circular topology network, wherein circular topology network comprises a plurality of buses, wherein each bus of the plurality of buses provides a plurality of slots for transmission of information,
• wherein processing nodes of the plurality of processing nodes are configured with phase-based arbitration constraints that regulate transmission information on the plurality of buses to the destination processing node only on a cycle that matches a phase window in which the destination processing node is allowed to receive the information on the plurality of buses;
• determining, by the arbiter in the processing node, that the source processing node has met a starvation condition when requesting transmission of the message, wherein the starvation condition is a predetermined amount of time the source processing node is unable to transmit a message,
• wherein a reservation policy for transmitting information on a communication bus of the plurality of buses according to the phase-based arbitration constraints is applied to the plurality of processing nodes when a processing node satisfies the starvation condition, the reservation policy defining a reservation window having a number of cycles that is determined in part by a most restrictive phase constraint of a processing node in the plurality of processing nodes, and the reservation policy resets at an end of the reservation window;
• placing, by the source processing node, a reservation for a given phase in a phase window onto a reservation bus of the plurality of buses, wherein the reservation adheres to the reservation policy restricting reservations between the plurality of processing nodes on the network, wherein the reservation is placed in a reserved slot allowed by the phase-based arbitration constraints of the destination processing node;
• observing, by the source processing node, a return corresponding to the reservation on the reservation bus providing the reserved slot for the message on the communication bus of the plurality of buses;
• and
• transmitting, by the source processing node, the message to the destination processing node in the reserved slot generated by the reservation.