As we've mentioned on the list earlier, we (I and Per Ottar Ribe Pahr) spent our last semester looking at Derby on multiprocessors and writing a report on what we found. We also promised to post it here in the hope that it is useful to someone, so here it is:
http://folk.ntnu.no/andersmo/derby_project_report.pdf I believe the general audience on derby-dev can skip chapter 2 without missing out on anything they don't already know. =) There are some things that didn't make it into the conclusion - most importantly this: B-tree latching is a significant bottleneck when the number of CPUs available grows to 8, and we believe it significant on 2 and 4 CPUs as well. Section 5.3.1 discusses this. The root block of the B-tree stands out as a significant contention point, see table 5.2. (The source data for said table actually included both latches and all regular locks in the lock manager - but nothing but latches made it into the top ten. =) We're currently looking more into at this very specific problem. Maybe we'll pass some more findings and suggestions on to you in a new report this summer - and any preliminary findings we believe to be significant might also be posted here on derby-dev. Thanks, -- Anders Morken My opinions may have changed, but not the fact that I am right!
