Re: Today Linus redesigns the networking driver interface (was Re: tulip driver in ...)

Alan Cox (alan@lxorguk.ukuu.org.uk)
Mon, 21 Sep 1998 16:52:18 +0100 (BST)

> First people wanted bottom half handling as a response to serial
> interrupts, because it made a huge difference to PPP latency. That already
> meant that some of the advantage of a bottom-half interrupt was no longer
> there. Then, with the new SMP code, it just became clear that it made no
> sense at all to have the difference, because the interrupt entry code
> became fairly involved (I definitely didn't want to have two separate
> copies).

and the people who first wanted it submitted patches that made irq handlers
return 1/0 according to if they needed a bh run. The instrastructure for that
is half in place in 2.1.1xx, so there's a valid 2.3.x project for anyone
who wants very fast irq handling there.

In truth for most of those cases running RTLinux is far simpler, far faster
and far more reliable since in the RTLinux case you _will_ hit your irq
latency deadlines not "most of the time".

Alan

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