Re: Kernel preemption, yes or no? (was: Filesystem gets a hugeperformance boost)

[E.B. Dreger]

> Date: Tue, 17 Apr 2001 19:06:08 -0700 (PDT)
> From: Matt Dillon <[EMAIL PROTECTED]>
> 
> They don't have to be.  If you have four NICs each one can be its own
> interrupt, each with its own mutex.  Thus all four can be taken in
> parallel.  I was under the impression that BSDI had achieved that
> in their scheme.

IIRC, didn't the NT driver for some NIC (Intel?) switch to polling,
anyway, under heavy load?  The reasoning being that you _know_ that you're
going to get something... why bother an IRQ hit?

That said, IRQ distribution sounds like a good thing for the general case.

> If you have one NIC then obviously you can't take multiple interrupts
> for that one NIC on different cpu's.  No great loss, you generally don't
> want to do that anyway.

Actually, I should think that one would _want_ to serialize traffic for a
given NIC.  (I'm ignoring when one trunks NICs... speaking of which,
anyone have info on 802.3ad? ;-)  Otherwise, one ends up with a race that
[potentially] screws up packet sequence.


Eddy

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