Multi-cast snoop vectors within a mesh topology
Techniques for sharing processor data within a network are disclosed. A system-on-a-chip (SOC) is accessed. The SOC includes a network-on-a-chip (NOC), which comprises an M×N mesh topology. The mesh includes a coherent tile at each mesh point. Each tile includes local snoop vectors (LSVs). A first coherent tile initiates a snoop operation. The tile generates a snoop vector that indicates other tiles to be notified of the snoop operation. The first coherent tile creates directional snoop vectors (DSVs). The creating logically combines the snoop vector with each of the LSVs. A coherent tile adjacent to the first coherent tile is selected. The adjacent tile is located in a cardinal direction from the first tile. A first DSV is chosen based on the cardinal direction. The first tile sends the snoop operation and the chosen first DSV to the selected adjacent tile.
1 . A processor-implemented method for sharing data comprising:
accessing a system-on-a-chip (SOC), wherein the SOC includes a network-on-a-chip (NOC), wherein the NOC includes an M×N mesh topology, wherein M and N are both integers greater than 1, wherein the M×N mesh topology includes a coherent tile at each point of the M×N mesh topology, and wherein each coherent tile in the M×N mesh topology includes one or more local snoop vectors (LSVs);
initiating, by a first coherent tile within the M×N mesh topology, a snoop operation;
generating, by the first coherent tile, a snoop vector, wherein the snoop vector indicates one or more other tiles within the M×N mesh topology to be notified of the snoop operation;
creating, by the first coherent tile, one or more directional snoop vectors (DSVs), wherein the creating includes logically combining the snoop vector that was generated with each of the one or more LSVs;
selecting an adjacent coherent tile to the first coherent tile, wherein the adjacent coherent tile is located in a cardinal direction from the first coherent tile;
choosing a first DSV from the one or more DSVs, wherein the choosing is based on the cardinal direction; and
sending, by the first coherent tile, to the adjacent coherent tile that was selected, the snoop operation and the first DSV that was chosen.
2 . The method of claim 1 further comprising generating, by the adjacent coherent tile, one or more second DSVs, wherein the generating includes logically combining the first DSV with each of one or more adjacent LSVs.
3 . The method of claim 2 wherein the logically combining is based on an AND function.
4 . The method of claim 2 further comprising identifying a second adjacent coherent tile, wherein the second adjacent coherent tile is located in a second cardinal direction from the adjacent coherent tile.
5 . The method of claim 4 wherein the second adjacent coherent tile is not the first coherent tile.
6 . The method of claim 5 further comprising picking a second DSV from the one or more second DSVs, wherein the picking is based on the second cardinal direction.
7 . The method of claim 6 further comprising forwarding, by the adjacent coherent tile, to the second adjacent coherent tile that was identified, the snoop operation and the second DSV that was picked.
8 . The method of claim 1 further comprising determining the one or more other tiles within the M×N mesh topology to be notified, wherein the determining is based on a directory-based snoop filter (DSF) within the first coherent tile.
9 . The method of claim 1 wherein the selecting includes a second adjacent coherent tile.
10 . The method of claim 9 wherein the choosing includes an additional DSV.
11 . The method of claim 10 further comprising transmitting, by the first coherent tile, the snoop operation and the additional DSV to the second adjacent coherent tile.
12 . The method of claim 1 wherein the one or more LSVs are based on a cardinal direction priority.
13 . The method of claim 12 wherein the cardinal direction priority is east/west, then north/south.
14 . The method of claim 1 wherein the coherent tile at each point of the M×N mesh topology comprises a switching unit (SU).
15 . The method of claim 1 wherein the first coherent tile includes a cache coherency block (CCB) and a coherency ordering agent (COA).
16 . The method of claim 15 wherein the adjacent coherent tile includes a CCB and a COA.
17 . The method of claim 15 wherein the adjacent coherent tile includes one or more memory control interfaces (MCIs).
18 . The method of claim 17 wherein the adjacent coherent tile does not receive the snoop operation or the first DSV that was chosen.
19 . The method of claim 15 wherein the adjacent coherent tile includes one or more I/O control interfaces (ICIs).
20 . The method of claim 1 wherein the one or more LSVs comprises four LSVs.
21 . The method of claim 20 wherein the four LSVs comprise a LSV for each of four cardinal directions from the first coherent tile.
22 . The method of claim 1 wherein the logically combining comprises a logical AND function.
23 . The method of claim 1 wherein the one or more LSVs are unique to the first coherent tile.
24 . The method of claim 1 wherein the NOC includes a point-to-point packetized communication protocol.
25 . The method of claim 1 wherein the snoop operation is an invalidating snoop operation.
26 . A computer program product embodied in a non-transitory computer readable medium for sharing data, the computer program product comprising code which causes one or more processors to generate semiconductor logic for:
accessing a system-on-a-chip (SOC), wherein the SOC includes a network-on-a-chip (NOC), wherein the NOC includes an M×N mesh topology, wherein M and N are both integers greater than 1, wherein the M×N mesh topology includes a coherent tile at each point of the M×N mesh topology, and wherein each coherent tile in the M×N mesh topology includes one or more local snoop vectors (LSVs);
initiating, by a first coherent tile within the M×N mesh topology, a snoop operation;
generating, by the first coherent tile, a snoop vector, wherein the snoop vector indicates one or more other tiles within the M×N mesh topology to be notified of the snoop operation;
creating, by the first coherent tile, one or more directional snoop vectors (DSVs), wherein the creating includes logically combining the snoop vector that was generated with each of the one or more LSVs;
selecting an adjacent coherent tile to the first coherent tile, wherein the adjacent coherent tile is located in a cardinal direction from the first coherent tile;
choosing a first DSV from the one or more DSVs, wherein the choosing is based on the cardinal direction; and
sending, by the first coherent tile, to the adjacent coherent tile that was selected, the snoop operation and the first DSV that was chosen.
27 . A computer system for sharing data comprising:
a memory which stores instructions;
one or more processors coupled to the memory wherein the one or more processors, when executing the instructions which are stored, are configured to:
access a system-on-a-chip (SOC), wherein the SOC includes a network-on-a-chip (NOC), wherein the NOC includes an M×N mesh topology, wherein M and N are both integers greater than 1, wherein the M×N mesh topology includes a coherent tile at each point of the M×N mesh topology, and wherein each coherent tile in the M×N mesh topology includes one or more local snoop vectors (LSVs);
initiate, by a first coherent tile within the M×N mesh topology, a snoop operation;
generate, by the first coherent tile, a snoop vector, wherein the snoop vector indicates one or more other tiles within the M×N mesh topology to be notified of the snoop operation;
create, by the first coherent tile, one or more directional snoop vectors (DSVs), wherein the creating includes logically combining the snoop vector that was generated with each of the one or more LSVs;
select an adjacent coherent tile to the first coherent tile, wherein the adjacent coherent tile is located in a cardinal direction from the first coherent tile;
choose a first DSV from the one or more DSVs, wherein the choosing is based on the cardinal direction; and
send, by the first coherent tile, to the adjacent coherent tile that was selected, the snoop operation and the first DSV that was chosen.