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From: Archie Cobbs <archie@whistle.com>
Message-Id: <199811151845.KAA02134@bubba.whistle.com>
Subject: Re: mpd + EQL, Livingston PM2 MLLB, alternatives? mpd load high?
In-Reply-To: <199811150024.AAA26739@woof.lan.awfulhak.org> from Brian Somers at "Nov 15, 98 00:24:46 am"
To: brian@Awfulhak.org (Brian Somers)
Date: Sun, 15 Nov 1998 10:45:49 -0800 (PST)
Cc: cshenton@uucom.com, dave@comsite.net, questions@FreeBSD.ORG
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Brian Somers writes:
> > > Archie: I notice mpd with one line is consuming 10-15% of my 486-66
> > > CPU when doing stuff like CVSUP or FTP downloads. Is this normal?  Due
> > > to the link compression?  Will it increase as I add lines?  The 486 is
> > > pretty much dedicated to being a dialup/router so this isn't a big
> > > concern but it does indicate scalability problems if I try to
> > > increase lines (or use even older hardware :-)
> > 
> > That's probably more or less normal.. the negative side of
> > doing it all in user-land.
> 
> A recent report from jak@cetlink.net (John Kelly) said about 
> user-ppp:
> 
> : >CPU loading under FTP is good with only one link in the bundle.  The
> : >server ppp consumes about 2% of the CPU and the client about 4%.  But
> : >when I add a second link to the bundle, the client ppp skyrockets to
> : >over 40% of the CPU.  Ouch!
> : 
> : I tried reversing the roles of client and server, and the problem
> : disappeared?!  Realizing that, I started swapping things and found
> : that one cable was causing the problem.  It was not obvious, because
> : throughput was fine with that cable.  But something about it is flakey
> : and causing the CPU load to shoot way up.
> : 
> : Now that I've replaced that cable, CPU loading is much better.  With
> : two lines running full blast at 115,200, the client tops out around 9%
> : and the server about 7%.  It goes much higher with compression, but I
> : can let the modems do the compression and save my CPU to run about 16
> : lines.
> 
> Maybe there's a similar problem with cabling here ?

Definitely could be.. for example, if you're not getting proper
flow control signals (RTS/CTS), or one of the data lines is flakey
and you get lots of corrupted packets, ...

-Archie

___________________________________________________________________________
Archie Cobbs   *   Whistle Communications, Inc.  *   http://www.whistle.com

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