Messages in this thread | | | Date | Sat, 2 Nov 2002 20:22:08 +0000 | From | Jamie Lokier <> | Subject | Re: rbtree scores (was Re: [patch] deadline-ioscheduler rb-tree sort) |
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Jens Axboe wrote: > > If it was worth it (I suspect not), you can make a data structure > > which has O(1) amortised insertion time for a number of common cases, > > such as runs of ascending block numbers. Seems a likely pattern for a > > filesystem... > > Fibonacci heaps, for instance. I looked into that as well. However, it's > actually more important to have (if possible) O(1) extraction than > insert. Extraction is typically run from interrupt context, when a > driver wants to requeue more requests because it has completed one (or > some). That was a worry with the rbtree solution. The linked list may > have had sucky O(N) insert, but extraction was a nice O(1). So far I > haven't been able to notice any regression in this area, regardless.
There's a skip list variant which offers O(1) extraction from the head of the list, and probabilistic O(log n) insertion, fwiw.
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