Hi, I'm sure there are lots of ways to optimise caching, but my question is: why does one process causing a lot of disk access slows down a whole lot other processes which you would think don't require so much disk access (like the Window Manager when you drag a window...). I haven't seen this kind of behaviour with other UNIX systems. John Hello! First of all, I don't know what is implemented in the darwin kernel at all, but here are some of my thoughts about this topic: Preventing disk access for starting applications if nearly impossible, because the data has to be read out for it. It can only be improved by caching all data that was read or reading out sequentially (if possible) data, that will be used. In an offline-situation it is possible to calculate what is the best way to read and cache disk-data, but in the online-situation it is somehow hard to tell which data could be read next. It is easy to guess if someone opens a file, that and begins to read it sequentially, that he could read the whole file, so the system could begin to cache it, if memory is available and no other disk-access is forced. This all shouldn't be a problem which is new to the world, so one should find some online-algorithms with a good competivness in the appropriate text-books. One question would be, how swapping is implemented. There has to be some way of telling the system, that the swap files don't have to be cached. Caching of swap-space is somehow stupid :) By using caches, one could also cache disk-write-access, trying to reduce disk-access at all, enhancing spin-down-times and for mobile users this should reduce battery usage. I was thinking of it some while ago, but hadn't had the time to look at the different parts of darwin related to disk-access. _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.