RE: [Xen-users] Problems with GPLPV network latency

["Nick Couchman" <Nick.Couchman@xxxxxxxxx>]

Can you remotely wipe out the machine and reinstall from scratch?  It could be 
a hardware issue or kernel issue, but it also may just be an odd setup issue - 
sometimes reinstalling just helps :-).

I'm running out of suggestions...the only times I've seen this have to do with 
transmission checksumming on certain network chipsets, and it's been a while 
since I've dealt with that.

-Nick

>>> "Ian Tobin"  06/23/10 3:40 PM >>>
Id love to run those tests but unfortunately the servers are in a DC 2
hour drive away so physical access is not available :(

Its really odd though, Dom0 network runs fine, no lags so the drivers
for the adapter are ok and also the DomU (windows) without the PV
drivers loaded works fine to.

So it looks like when ever there is XEN driver loaded for the network it
seems to upset things.  The other thing i haven't tried is to build a
HVM linux DomU and see what that does.

Its really like the drivers can't talk through the bridge correctly.  By
the sounds of things im the only one with this issue but the hardware is
nothing out of the ordinary.

Thanks

Ian


-----Original Message-----
From: Nick Couchman [mailto:Nick.Couchman@xxxxxxxxx] 
Sent: 23 June 2010 16:11
To: james.harper@xxxxxxxxxxxxxxxx; xen-users@xxxxxxxxxxxxxxxxxxx; Ian
Tobin
Subject: RE: [Xen-users] Problems with GPLPV network latency

Hmmm...so, possible reasons for this are:
- Network chipset on motherboard is slightly different and causes
problems
- There's some change between 2.6.32.13 and 2.6.32.14 with networking
that causes problems.

If you're in a position to run a couple of tests, I'd suggest the
following: swap hard drives between this machine that's causing problems
and one of the ones that's working fine and see what the result is.  If
they're similar enough, booting should work fine and you should be able
to do a quick test.  Of course, I have to offer the advice to back up
before attempting this :-).

-Nick

>>> On 2010/06/23 at 09:00, "Ian Tobin"  wrote: 
> This box is running a newer kernel than the rest.
> 
> The other are running 2.6.32.13 while this is running 2.6.32.14.  The
> motherboards just have different chipsets but are AMD boards.
> 
> 
> 
> -----Original Message-----
> From: Nick Couchman [mailto:Nick.Couchman@xxxxxxxxx] 
> Sent: 23 June 2010 15:55
> To: james.harper@xxxxxxxxxxxxxxxx; xen-users@xxxxxxxxxxxxxxxxxxx; Ian
> Tobin
> Subject: RE: [Xen-users] Problems with GPLPV network latency
> 
> And they're all running the same version of Xen and the dom0 kernel?
> 
> At this point, I'm just trying to highlight differences that may be
> causing this.  If you're running identical kernels, I highly doubt the
> bridge mode is to blame, since that's part of the dom0 kernel.  If the
> kernels are different, than it could be the bridge module or the
module
> for the specific network chipset you're using.
> 
> When you say the MBs are slightly different, do you know what those
> differences are?
> 
> -Nick
> 
>>>> On 2010/06/23 at 08:46, "Ian Tobin"  wrote: 
>> Hi,
>> 
>> No I have 5 servers. This is the only one im facing this issue with, 
>> all built the same though this motherboard is slightly different.  I 
>> don't have any problems with Dom0 out to the internet and back, its 
>> just the DomUs.  Im using bridged mode so could it be that the bridge

>> is at fault?
>> 
>> Its strange why only the Windows DomU will work with no network 
>> driver, just the standard one.
>> 
>> Im running XEN 4.0 on 2.6.32.14 kernel, the chipset is AMD 740G / AMD
>> SB700 (http://www.pcwb.co.uk/catalogue/item/A0477614?cidp=Froogle)
>> 
>> Thanks
>> 
>> Ian
>> 
>> 
>> 
>> -----Original Message-----
>> From: Nick Couchman [mailto:Nick.Couchman@xxxxxxxxx]
>> Sent: 23 June 2010 14:52
>> To: james.harper@xxxxxxxxxxxxxxxx; xen-users@xxxxxxxxxxxxxxxxxxx; Ian

>> Tobin
>> Subject: RE: [Xen-users] Problems with GPLPV network latency
>> 
>> Do you only have one Xen server running - the one you're having 
>> problems with?  Or do you have multiple servers running, and all of 
>> them are having problems?  O r multiple ones running and only this
one
> 
>> is seeing this problem?
>> 
>> What's the chipset of the network cards in your physical machine?  
>> Also, I'm sure you've already posted it, but remind me what versions 
>> of Xen and the dom0 kernel you're running.
>> 
>> -Nick
>> 
>>>>> "Ian Tobin"  06/23/10 4:33 AM >>>
>> Hi,
>> 
>> Ive built a linux DomU and am facing the same network issue, massive 
>> delays then no network at all so its not limited to Windows DomUs.
It
> 
>> seems that the only DomU to work is one which doesn't have the XEN 
>> drivers running.
>> 
>> Any ideas?
>> 
>> Thanks
>> 
>> Ian
>> 
>> -----Original Message-----
>> From: James Harper [mailto:james.harper@xxxxxxxxxxxxxxxx]
>> Sent: 09 June 2010 14:03
>> To: Nick Couchman; xen-users@xxxxxxxxxxxxxxxxxxx; Ian Tobin
>> Subject: RE: [Xen-users] Problems with GPLPV network latency
>> 
>>> James,
>>> What config options adjust the timer in Xen?
>>> 
>> 
>> It's timer_mode I think. I'm not sure what all the different values 
>> mean though.
>> 
>> James
>> 
>> 
>> 
>> 
>> 
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