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    SubjectRe: Why is 2.4.32 four times faster than
    On Sun, 8 Jan 2006 18:37:52 -0800, Jesse Brandeburg <> wrote:

    >On 1/8/06, Grant Coady <> wrote:
    >> On Sun, 08 Jan 2006 11:23:37 +0100, (Bernd Eckenfels) wrote:
    >> >Willy Tarreau <> wrote:
    >> >> It's rather strange that 2.6 *eats* CPU apparently doing nothing !
    >> >
    >> >it eats it in high interrupt load. And it is caused by the pty-ssh-tcp
    >> >output, so most likely those are eepro100 interrupts.
    >> That would be true for either 2.4 or 2.6, no? Also it runs e100
    >> driver, but...
    >> 2.4 dmesg:
    >> Intel(R) PRO/100 Network Driver - version 2.3.43-k1
    >> Copyright (c) 2004 Intel Corporation
    >> e100: selftest OK.
    >> e100: eth0: Intel(R) PRO/100 Network Connection
    >> Hardware receive checksums enabled
    >> cpu cycle saver enabled
    >> 2.6 dmesg:
    >> [ 31.977945] e100: Intel(R) PRO/100 Network Driver, 3.4.14-k2-NAPI
    >> [ 31.978007] e100: Copyright(c) 1999-2005 Intel Corporation
    >> [ 32.002928] e100: eth0: e100_probe: addr 0xfd201000, irq 11, MAC addr 00:90:27:42:AA:77
    >> [ 32.026992] e100: eth1: e100_probe: addr 0xfd200000, irq 12, MAC addr 00:90:27:58:32:D4
    >> [ 32.186941] e100: eth0: e100_watchdog: link up, 100Mbps, full-duplex
    >> Are rx checksums not turned on in 2.6' e100 driver?
    >> CPU is only pentium/mmx 233
    >Hey Grant, to answer your question, checksums are not offloaded with
    >the current e100 driver but that really shouldn't make that much of a
    >difference. I'm actually going to go with interrupt load due to e100
    >being at least related to the problem.

    Okay, that may make a difference with a slow CPU.

    >BTW I get access denied when hitting

    OMG! Not the red screen? Hmmm, collateral damage ;) Just turned it
    off, unless you're masquerading as a web crawler :p

    >The netdev-2.6 git tree currently has a driver that supports microcode
    >loading for your rev 8 PRO/100 and that microcode may help your
    >interrupt load due to e100. however, it may already be loading.

    >Also, what do you have HZ set to? (250 is default in 2.6, 1000 in 2.4)
    >so you could try running your 2.6 kernel with HZ=1000

    Running it with 100Hz, isn't 2.4 == 100Hz? I can try 1000Hz,
    but not for some hours now, other stuff on.

    >while you're running your test you could try (if you have sysstat)
    >sar -I <e100 interrupt> 1 10
    >or a simpler version, 10 loops of cat /proc/interrupts; sleep 1;
    >Lets see if its e100,

    Yes, lets. More later.

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