Re: e1000 1sec latency problem

[Max Krasnyansky <maxk@qualcomm.com>]

Pavel Machek wrote:
> Hi!
> 
> I have the famous e1000 latency problems:
> 
> 64 bytes from 195.113.31.123: icmp_seq=68 ttl=56 time=351.9 ms
> 64 bytes from 195.113.31.123: icmp_seq=69 ttl=56 time=209.2 ms
> 64 bytes from 195.113.31.123: icmp_seq=70 ttl=56 time=1004.1 ms
> 64 bytes from 195.113.31.123: icmp_seq=71 ttl=56 time=308.9 ms
> 64 bytes from 195.113.31.123: icmp_seq=72 ttl=56 time=305.4 ms
> 64 bytes from 195.113.31.123: icmp_seq=73 ttl=56 time=9.8 ms
> 64 bytes from 195.113.31.123: icmp_seq=74 ttl=56 time=3.7 ms
> 
> ...and they are still there in 2.6.25-git0. I had ethernet EEPROM
> checksum problems, which I fixed by the update, but problems are not
> gone.
> 
> irqpoll helps.
> 
> nosmp (which implies XT-PIC is being used) does not help.
> 
>  16:       1925          0   IO-APIC-fasteoi   ahci, yenta, uhci_hcd:usb2, eth0
> 
> Booting kernel with nosmp/ no yenta, no usb does not help.
> 
> Hmm, as expected, interrupt load on ahci (find /) makes latencies go
> away.
> 
> It should be easily reproducible on x60 with latest bios, it is 100%
> reproducible for me...

So you don't think it's related to the interrupt coalescing by any chance ?
I'd suggest to try and disable the coalescing and see if it makes any difference.
We've had lots of issues with coalescing misbehavior. Not this bad (ie 1 second) though.

Add this to modprobe.conf and reload e1000 module

options e1000 RxIntDelay=0,0 RxAbsIntDelay=0,0 InterruptThrottleRate=0,0 TxIntDelay=0,0 TxAbsIntDelay=0,0

Max