RE: em0, polling performance, P4 2.8ghz FSB 800mhz

From: Don Bowman (don_at_sandvine.com)
Date: 02/29/04

  • Next message: Deepak Jain: "Re: em0, polling performance, P4 2.8ghz FSB 800mhz" 
    To: 'Deepak Jain' <deepak@ai.net>, freebsd-hackers@freebsd.org
Date: Sat, 28 Feb 2004 21:19:18 -0500

    > I have a machine running 4.9. P4 2.8Ghz, 800mhz bus, Intel PRO/1000
    > ethernet connected to a Cisco, both sides are locked to 1000/FD.
    >
    > The kernel has HZ=1000, and DEVICE_POLLING, IPFW, DUMMYNET,
    > etc. After
    > only a few minutes of run time under an attack ~90,000 pps.
    > The attack
    > has been limited at the router to JUST incoming TCP port 80 inbound
    > traffic. I don't know why the machine is having such a hard
    > time under
    > the load. The cpu shows it is >90% idle even under the worst of the
    > attack. What am I doing wrong?

    I think there's a problem with CPU time not getting properly
    accounted for in device polling, so it may be busier than you think.

    For this scenario, i would set net.inet.tcp.blackhole=2. You
    might be spending a lot of time creating the ICMP unreachable
    messages, rather than in the network driver (where device polling
    would help).

    --don
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  • Next message: Deepak Jain: "Re: em0, polling performance, P4 2.8ghz FSB 800mhz"

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