Graphically this looks the same as a mesh. How is it really different? Is it just that the nodes on the edge of the network have extra connections?
This comment was marked helpful 0 times.
drayson
Yes, I believe that's the case -- it's basically a mesh but with extra "wrap-around" links from the node on the end of a row/column to the node at the other end of that row/column.
This comment was marked helpful 0 times.
pinkertonpg
One important thing to note is the last bullet - unequal link lengths. For certain arrangements, it may be possible that the wraparound links are similar in length to the other links, but in most cases, these links have to traverse much more space. The chips we use typically (exception noted a few slides ahead I believe) are 2D-ish, so these wraparound links are not as simple as shown on the slide.
This comment was marked helpful 0 times.
jon
Wraparound links are one way in which engineering complexity can be traded off for better performance (i.e., smaller average hop distance).
There have been proposals for more complicated networks based on the torus. One example is the iBT network (research paper, picture). iBT adds more links to the torus, further shortening diameter and average hop distance. On the other hand, it is almost certainly more costly to build in practice.
Graphically this looks the same as a mesh. How is it really different? Is it just that the nodes on the edge of the network have extra connections?
This comment was marked helpful 0 times.
Yes, I believe that's the case -- it's basically a mesh but with extra "wrap-around" links from the node on the end of a row/column to the node at the other end of that row/column.
This comment was marked helpful 0 times.
One important thing to note is the last bullet - unequal link lengths. For certain arrangements, it may be possible that the wraparound links are similar in length to the other links, but in most cases, these links have to traverse much more space. The chips we use typically (exception noted a few slides ahead I believe) are 2D-ish, so these wraparound links are not as simple as shown on the slide.
This comment was marked helpful 0 times.
Wraparound links are one way in which engineering complexity can be traded off for better performance (i.e., smaller average hop distance).
There have been proposals for more complicated networks based on the torus. One example is the iBT network (research paper, picture). iBT adds more links to the torus, further shortening diameter and average hop distance. On the other hand, it is almost certainly more costly to build in practice.
This comment was marked helpful 0 times.