Low Throughput / High CPU Load



  • Hi there!

    I'm using PfSense 2.0 for some time now with an Futro S200 containing a Transmeta Crusoe 800Mhz CPU and a dual Gigabit Intel NIC (em). When I got a new broadband internet connection (64Mbit), I noticed that  this speed could not be reached at all. When I run iperf I'll only get a maximum throughput of about 48-55Mbit and 100% CPU (system) load. I already tried other NICs but the Problem persists. Is that a driver Problem or is the 800Mhz CPU really to slow to make more than 50 Mbit? Are there any know problems with the em driver? Packets don't even go through the system, its a simple LAN side so filtering etc. should not touch performance, don't it?

    Thanks for your help!



  • In the firewall, the packet come in one nic, is evaluated, and goes out another inc.  The "is evaluated" part is the problem.  Yes, you are hitting the limits on the CPU.  To get better speeds you will need Atom at a minimum, and a good one at that.  Or a real P4 or better CPU.



  • Transmeta Crusoe CPUs are ridiculously slow.  They actually emulate an x86 architecture (note: not 100%) through some interesting but poorly-implemented code morphing, so the performance you'd expect from an 800Mhz Celeron or similar is nowhere near what you get with the Crusoe.  I'm actually surprised you saw 55Mbit/s.



  • @Lee:

    To get better speeds you will need Atom at a minimum, and a good one at that.  Or a real P4 or better CPU.

    Not really. Yes it's maxing out the CPU in this case, but not because it's a load that requires a significant CPU, more that it's an absurdly slow CPU. An 800 MHz Celeron would smoke that Crusoe. An 800 MHz P3 even more so. Even a 500 MHz Geode in an ALIX would be significantly faster. A PII 300 or so would be as well.



  • But he is talking about gigabit speeds, and to get 500mbps you really needs some horsepower.  A new Atom dual core will do it.  A first generation will hit about 150mbps.  Maybe 200mbps down hill with a wind…



  • @Lee:

    But he is talking about gigabit speeds, and to get 500mbps you really needs some horsepower.  A new Atom dual core will do it.  A first generation will hit about 150mbps.  Maybe 200mbps down hill with a wind…

    Oh sure, for gigabit yeah. He's talking about a 64 Mbps Internet connection though unless I missed something.



  • Woops…  64 meg connection and a gigabit card.  I got confused.  But the information is still good for the next guy. :)



  • So thanks for your replies! I guess I really need to find a different hardware for my router then… I really thougth/hoped this could be a driver problem. ;) Any cheap hardware (preferably a ready to go thin client) recommendation which will handle around 100 Mbit and do some filtering and statistics?



  • If you don't mind the size, there are tons of Dell Optiplex mini-tower boxes on eBay with Core 2 Duo CPUs for ~$100 that are more than adequate.



  • Two directions…

    Get an old desktop.  Anything P4 dual core or better, and you are fine.  Actually, you could do single core, but not have much room to grow.

    Get a new small form factor.  Newer Atom systems with the 3 port Intel NIC daughter card.  Quiet, fanless, and gigabit support.  Not cheap.



  • I got a real cheap Igel Thinclient with Via C7 1ghz from eBay. I think it will be fine for me right now. I was just "missing" 10mbit, So I guess this small Hardware Upgrade will do fine ;)

    So thanks for your help!


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