toad wrote: > Well there are two issues here: > 1. Simulations don't seem to show a consistent lead for backoff plus > throttling over just throttling. At least, recent ones - do yours? If > this is true, then why?
Recent simulations show that backoff plus throttling and throttling alone are pretty evenly matched. I would guess this is because throttling keeps load at a low enough level that backoff rarely occurs. That would also explain why backoff alone slightly outperforms the other two mechanisms when there are slow nodes - backoff is a local reaction to overload whereas throttling is a global reaction, so backoff misroutes around the slow nodes, whereas throttling slows down the whole network. > 2. Why is the real network so slow? It uses far less bandwidth than the > specified limit; this suggests that the throttling has gone mad, or > something (pre-emptive rejection) has broken it. Can we reproduce this > in the simulation, and show why it happens / that it doesn't happen if > we slightly change things? I hope so, but there are a lot of places a bug could be hiding. Are there any clues in the logs about what's triggering RejectedOverloads? At one point inserts were much slower than requests - is that still the case? Is the insert throttle slower than the request throttle, and if so, why are inserts more likely to trigger RejectedOverloads than requests are? Cheers, Michael
