Am Freitag, 15. April 2005 22:58 schrieb Alan Stern:
> > > > It's true that other changes I have planned for the driver will reduce
> > > > these values, although it's impossible to predict by how much. �However
> > > > I
> > > > think this gives a pretty good indication that splitting the driver
> > > > into a
> > > > top- and bottom-half is worth considering.
> > >
> > > Why? The worst case is in enqueue. �Enqueing is not always interrupt
> > > driven.
> >
> > IRQ handling is though ... :)
>
> The point is not whether things are interrupt-driven, it's whether or not
> interrupts are enabled. �In a bottom-half handler all the time-consuming
> work can be done with interrupts enabled.
How so? Part of the work done in IRQ can be shifted to tasklets, yes.
But the enqueue times are worse, so are in more need of optimisation.
So instead of shifting code in the enqueue path to a different lock,
shifting it under no lock or into another path at all would seem better
to me.
Regards
Oliver
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