lkml.org 
[lkml]   [2008]   [Jun]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Strange problem with e1000 driver - ping packet loss
Srivatsa Vaddagiri wrote:
> Hi,
> I happened to look at a system which was exhibiting poor ping
> performance with e1000 driver (in 2.6.25) and had some questions regarding that.
>
> Ping test was done between the system and a laptop, which were connected
> using a straight ethernet cable. Ping reported round trip times running
> into seconds (!) and also packet loss.
>
> Upon some investigation, I found that the interrupt count field in
> /proc/interrupts (associated with eth1) is not incrementing as fast as
> it should. Moreover eth1 interrupt line is shared with the hard disk
> interrupt (ata_piix) as below:
>
> # cat /proc/interrupts
>
> .
>
> 10: 2296 XT-PIC-XT ata_piix, eth0, eth1
>
> .
>
> IRQ10 is thus being shared by both the hard disk and eth0/eth1.
>
> Here's the strange observation I made:
>
> When I initiate some disk activity (ex: dd if=/dev/zero of=/tmp/file), ping
> performance suddently shot up (round trip time in double digits ms, 0% packet
> loss)! I presume this is because that e1000 intr handler is called
> whenever there was a interrupt from hard disk on IRQ10, which polled
> NIC and processed packets immediately.
>
> As soon as I kill the background disk-write intensive job, ping
> performance again dropped.
>
> This meant that e1000 NIC is having trouble interrupting the OS.
>
> Before I could jump up and say this is a hardware issue, I was told
> that Windows works just fine on the server (and as well as 2.4 kernel,
> which I couldnt verify) :(
>
>
> Some more observations:
>
> 1. I tried setting e1000 parameters (RxIntDelay=0, RxAbsIntDelay=0,
> TxIntDelay=0, TxAbsIntDelay=0, InterruptThrottleRate=0). None of
> them helped.
>
> 2. When ping performance was poor, readprofile showed that system
> is mostly idle. This confirms that OS is not getting very
> frequenty interrupts from eth1 and hence idling.
>
> 3. When ping performance was poor, ethtool -S eth1 showed that
> rx_bytes was incrementing at a good pace, showing that the
> NIC was receiving ping responses back, but not handing them over
> to OS for further processing
>
> 4. e1000 chipset is 82546GB
>
> 5. e1000e driver didnt work at all (it doesnt recognize the cards).
>
>
> Any advice on how to fix this problem?

Can you post your dmesg output from bootup with no special options
(noacpi, etc.) enabled?


\
 
 \ /
  Last update: 2008-06-19 19:31    [W:0.121 / U:0.760 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site