Messages in this thread |  | | Date | Tue, 9 Jun 2015 10:05:56 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [patch 2/7] timer: Remove FIFO guarantee |
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On Tue, 9 Jun 2015, George Spelvin wrote: > Thomas Gleixner wrote: > > > After thinking more about it, I'm even more sure that any code which > > relies on the FIFO "guarantee" is broken today. > > Indeed, I am completely convinced. All I might request is a reassignment > of blame in the commit message.
Will do. Thanks for spotting it!
> Thank you for your comments on my other blue-sky ideas, too. > > I need to look into why we're using wheels, and what the point is. > How much of an advantage do they have over an efficient priority queue > like a pairing heap?
The only reason is performance. The wheel has O(1) insertion and deletion time while heaps and trees usually have O(log(n)).
Timer wheel timers are usually timeouts and 99% of them are canceled before expiry. Networking is probably the heaviest use case followed by disk I/O.
Thanks,
tglx
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