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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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