US 6,888,843 B2 · Response virtual channel for handling all responses

Abstract

A computer system employs virtual channels and allocates different resources to the virtual channels. Packets which do not have logical/protocol-related conflicts are grouped into a virtual channel. Accordingly, logical conflicts occur between packets in separate virtual channels. The packets within a virtual channel may share resources (and hence experience resource conflicts), but the packets within different virtual channels may not share resources. Since packets which may experience resource conflicts do not experience logical conflicts, and since packets which may experience logical conflicts do not experience resource conflicts, deadlock-free operation may be achieved. Additionally, nodes within the computer system may be configured to preallocate resources to process response packets. Some response packets may have logical conflicts with other response packets, and hence would normally not be allocable to the same virtual channel. However, by preallocating response-processing resources, response packets are accepted by the destination node. Thus, any resource conflicts which may occur are temporary (as the response packets which make forward progress are processable). Viewed in another way, response packets may be logically independent if the destination node is capable of processing the response packets upon receipt. Accordingly, a response virtual channel is formed to which each response packet belongs.

Claims39

Dependent claims

A method for routing packets among a plurality of nodes in a computer system, the method comprising:

receiving a first response packet in a first node of said plurality of nodes, said first node comprising a plurality of control packet buffers, each of said plurality of control packet buffers assigned to a different one of a plurality of virtual channels;
storing said first response packet in a response buffer which is one of said plurality of control packet buffers, said plurality of control packet buffers further including at least two additional control packet buffers corresponding to at least two additional virtual channels of said plurality of virtual channels, wherein said first response packet is a response to a first control packet belonging to one of said at least two additional virtual channels, and wherein said storing said first response packet in said response buffer is independent of which one of said at least two additional virtual channels said first control packet belongs to;
receiving a second response packet in said first node, said second response packet a response to a second control packet belonging to a different one of said at least two virtual channels from said first control packet;
and
storing said second response packet in said response buffer.

2 more elements

A computer system comprising:

a first node configured to transmit a first response packet;
and
a second node coupled to receive said first response packet from said first node, wherein said second node comprises:
a response buffer assigned to a response virtual channel;
a first control packet buffer assigned to a first virtual channel different from said response virtual channel;
and
a second control packet buffer assigned to a second virtual channel different from said response virtual channel and said first virtual channel;
wherein said response packet is a response to a first control packet belonging to one of said first virtual channel and said second virtual channel, and wherein said second node is configured to store said first response packet in said response buffer independent of which of said first virtual channel and said second virtual channel to which said first control packet belongs, and wherein said second node further comprises a response data buffer configured to store response data packets specified by response packets, and wherein said first node is configured to transmit a first response data packet specified by said first response packet, and wherein said second node is configured to store said first response data packet in said response data buffer.

5 more elements

A node comprising:

one or more response buffers assigned to a response virtual channel;
one or more first control packet buffers assigned to a first virtual channel different from said response virtual channel;
and
one or more second control packet buffers assigned to a second virtual channel different from said response virtual channel and said first virtual channel;
wherein, in response to receiving a first response packet that is a response to a first control packet belonging to one of said first virtual channel and said second virtual channel, the node is configured to store said first response packet in said response buffers independent of which of said first virtual channel and said second virtual channel to which said first control packet belongs, and wherein said node further comprises one or more response data buffers configured to store response data packets specified by response packets, and wherein, in response to receiving a first response data packet specified by said first response packet, said node is configured to store said first response data packet in said response data buffers.

2 more elements

Dependencies are inferred from the claim text.

Response virtual channel for handling all responses

Life of this patent

Response virtual channel for handling all responses

Life of this patent

Abstract

Claims39