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List: freebsd-hackers
Subject: Re: IP queue question
From: Luigi Rizzo <rizzo () aciri ! org>
Date: 2001-12-28 18:18:20
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On Fri, Dec 28, 2001 at 11:55:36AM -0500, sridharv@ufl.edu wrote:
> is there any specific advantage in using
> device_polling method? does is give sth other than
> fairness? or is the multiple queue a 100% a;ternative?
> can u tell me a bit more about inline processing? or
> pointers to text would also do
sorry, i forgot... have a look at http://www.iet.unipi.it/~luigi/polling/
cheers
luigi
> cheers
> s
> Quoting Luigi Rizzo <rizzo@aciri.org>:
>
> > Hi,
> > FreeBSD uses a single queue, but as long as you make
> sure that you
> > do not fill the queue with packets coming from a
> single interface,
> > you can still give some fairness to the system.
> Recent "DEVICE_POLLING"
> > code in -current (hopefully going into -stable at
> some point) does
> > exactly this -- an alternative way, which is not
> terribly hard to
> > implement, could be to put packets from each
> interface into a
> > separate queue as Comer suggests, and then going
> round-robin on
> > these queues upon the software interrupt.
> >
> > As for the soft interrupt going away soon, this
> won't happen, there
> > are pros and cons for using delayed processing so
> the goal is to
> > augment the mechanism with inline processing, not
> replace it.
> >
> > cheers
> > luigi
> >
> > On Fri, Dec 28, 2001 at 01:40:00AM -0500,
> sridharv@ufl.edu wrote:
> > > I was reading TCP/IP Vol 2 by douglas comer. In
> that
> > > he has one queue for each interface from which the
> IP
> > > layer processes the incoming datagrams. He has used
> > > round-robin for fairness. I checked up the BSD code
> > > and it seems to use only one queue 'ipintrq'. The
> > > ethernet driver places the mbuf in this queue for
> an
> > > IP payload. Comer has also asked a review question
> > > pertaining to the disadvantage of having a single
> > > queue ( which i presume inhibits fair scheduling
> and
> > > stuff)
> > > Have I interpreted the code correctly? Y is this
> so in
> > > BSD?
> > > Also when I took a look at FreeBSD ipinput code the
> > > ipintr function which handles the software
> interrupt
> > > had a comment which said " to go away sometime
> soon" .
> > > Why and what is the alternative?
> > >
> > > The fastest way to change is to laugh at your own
> > > folly - Who moved my cheese
> > >
> > > To Unsubscribe: send mail to majordomo@FreeBSD.org
> > > with "unsubscribe freebsd-hackers" in the body of
> the message
> >
>
>
>
> The fastest way to change is to laugh at your own
> folly - Who moved my cheese
>
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