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Date:      Fri, 13 Jul 2001 13:14:43 -0700
From:      Terry Lambert <tlambert2@mindspring.com>
To:        Bernd Walter <ticso@mail.cicely.de>
Cc:        Leo Bicknell <bicknell@ufp.org>, freebsd-hackers@FreeBSD.ORG
Subject:   Re: Network performance roadmap.
Message-ID:  <3B4F56B3.575C5032@mindspring.com>
References:  <20010713101107.B9559@ussenterprise.ufp.org> <3B4F4534.37D8FC3E@mindspring.com> <20010713151257.A27664@ussenterprise.ufp.org> <20010713215956.A20320@cicely20.cicely.de>

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Bernd Walter wrote:
> 
> On Fri, Jul 13, 2001 at 03:12:57PM -0400, Leo Bicknell wrote:
> > On Fri, Jul 13, 2001 at 12:00:04PM -0700, Terry Lambert wrote:
> > > One good way to prevent this is to not unreasonably set
> > > your window size... 8-p.
> >
> > Ah, I see, so to prevent MBUF exhaustion I should not let
> > my socket buffers get large.  Sort of like to prevent serious
> > injury in a car crash I should drive at 10MPH on the freeway.
> >
> > Performance limits to save a system from crashing should be
> > a last resort.
> 
> One point is that if a client gets serviced with more performance
> the system can reuses the buffers much sooner.

There is a scheduling algorithm for network traffic that
attempts to schedule fastest completion first on requests;
there is a nice paper on this available from CMU.  It turns
out that it does not stall the big requests unreasonably,
and substantially improves overall throughput.

Julian's nifty approach basically controlled the queue size
on the sender by being extremely tricky on the receiver,
which enabled him to guarantee QOS for various types of
data flows, without congesting intermediate hop routers
unduly.  I let him talk about it if he wants, but I will
not say any more without his permission (and with it will
probably still defer to him 8-)).

-- Terry

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