Just in time distributed transaction crediting

A computer system, comprising:

• one or more source clients;
• a destination client;
• and a crossbar unit, including one or more source arbiters, coupled to the one or more source clients and the destination client and configured to perform the steps of:
• receiving, at a crossbar unit, a first data packet from a first source client for transmission to the destination client, wherein the first source client is associated with a first source arbiter that includes an first quantity of credits needed to transmit data packets;
• determining whether at least one credit in the first quantity of credits is available;
• if at least one credit in the first quantity of credits is not available, then storing the first data packet in a local memory;
• or
• if at least one credit in the first quantity of credits is available, then:
• consuming one credit from the first quantity of credits,
• transmitting the first data packet from the destination credit management unit to the destination client for storage in a first unit of memory space within the destination client,
• determining whether at least one credit stored in a second quantity of credits is available for transmission to the first source arbiter, wherein the second quantity of credits comprises a shared credit pool in the destination credit management unit that is shared among the one or more source clients, and
• if at least one credit in a second quantity of credits is not available, then:
• not transmitting any credits to the first source arbiter when a credit is unavailable for transmission to the first source arbiter;
• and
• adding an identifier associated with the first source client to a waiting client buffer, or,
• if at least one credit in a second quantity of credits is available, then transmitting a credit from the second quantity of credits to the first source arbiter for storage in the first quantity of credits.