Date: Tue, 26 Feb 2008 11:48:47 +0200 From: Nikos Vassiliadis <nvass@teledomenet.gr> To: freebsd-questions@freebsd.org Cc: Dylan Smith <dylan@lightray.org> Subject: Re: Normal CPU usage with a PPP connection Message-ID: <200802261148.47946.nvass@teledomenet.gr> In-Reply-To: <47C1645D.1040703@lightray.org> References: <47C1645D.1040703@lightray.org>
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On Sunday 24 February 2008 14:34:37 Dylan Smith wrote: > Hey guys, i'm running 6.3-R with (i think) userland ppp to connect to my > ADSL provider over PPPoE. > I build a number of graphs(mrtg) for system stats and i am noticing that > under heavy load on my ppp connection, that is sustained 150KB/s for an > hour or so my cpu usage, based on my graph, hovers around 20% (haven't > looked at it in top yet but if there isn't a simple solution/reason for > this i will look into what sort of usage it is). You should check top and tcpdump, it might be a big number of small packets causing the load. > The box is a home > router/server so at any 1 time isn't doing anything else that i can see > would account for this. I also noticed that this usage increase does not > occur with traffic coming/going on the inward facing interface, which > regularly has transfer speeds around 10 MB/s. > > I'm running a AMD X2 3800+ with 2GB ram. Is this sort of usage normal? Can't really tell if it's normal, but it is known that userland ppp uses much resources. I have seen it too using 20% CPU time running on a much slower machine(I faintly remember that it was a Pentium Celeron at 300MHz) and a much slower(384/128?) ADSL line. > Is there something i can do to bring it down? Fortunately yes, you could use net/mpd. The CPU load then, will probably be near zero for normal traffic, the 150KB/s you mention. If a million of small packets arrive at your router the load will be higher, nevertheless orders of magnitude lower than the load caused by userland ppp. HTH, Nikos
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