I\'m writing a library where:
A first step towards cache line efficiency is to provide for referential locality (i.e. keeping your data close to each other). This is hard to do in JAVA where almost everything is system allocated and accessed by reference.
To avoid references, the following might be obvious:
These rules will at least ensure some referential locality when working on a single object and when traversing the object references in your object graph.
Another approach might be to not use object for your data at all, but have global non-ref typed arrays (of same size) for each item that would normally be a field in your class and then each instance would be identified by a common index into these arrays.
Then for optimizing the size of the arrays or chunks thereof, you have to know the MMU characteristics (page/cache size, number of cache lines, etc). I don't know if JAVA provides this in the System or Runtime classes, but you could pass this information as system properties on start up.
Of course this is totally orthogonal to what you should normally be doing in JAVA :)
Best regards