Messages in this thread | | | Date | Wed, 13 Sep 2006 08:14:40 +0200 | From | Jens Axboe <> | Subject | Re: [PATCH 11/20] nbd: request_fn fixup |
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On Tue, Sep 12 2006, Jeff Garzik wrote: > Jens Axboe wrote: > >Generally the block device rule is that once you are invoked due to an > >unplug (or whatever) event, it is the responsibility of the block device > >to run the queue until it's done. So if you bail out of queue handling > >for whatever reason (might be resource starvation in hard- or software), > >you must make sure to reenter queue handling since the device will not > >get replugged while it has requests pending. Unless you run into some > >software resource shortage, running of the queue is done > >deterministically when you know resources are available (ie an io > >completes). The device plugging itself is only ever done when you > >encounter a shortage outside of your control (memory shortage, for > >instance) _and_ you don't already have pending work where you can invoke > >queueing from again. > > Or he could employ the blk_{start,stop}_queue() functions, if that model > is easier for the driver (and brain).
Definitely, yes.
-- Jens Axboe
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