DragonFly BSD
DragonFly kernel List (threaded) for 2003-07
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Re: just curious

From: Peter da Silva <peter-dragonfly@xxxxxxxxxxx>
Date: Thu, 17 Jul 2003 18:05:10 -0500

I think implementing support for multiple requests is much easier than
exporting it under a normal API.

Well, for "a normal API" read "a traditional UNIX API". I don't see any reason the Dragonfly API couldn't be used directly by applications.

However, there isn't really any support on clients for say stat file x - if it has changed read bytes i - j and then write z to byte k.

Ah, this is the same problem, basically, as out-of-order scheduling at the processor "microcode" level. If there's a dependency in the scheduling you get a bubble in the pipeline: in this case the read and write are dependant on the stat, so they can execute in parallel but they can't start until the stat completes... *or* you can schedule the read anyway and throw the data away if the stat fails... and the optimum strategy is different depending on the relative cost of the operations and how close to the critical path they are.

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