RE: [Xen-users] GPLPV drivers block when copying huge files

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> Hi,
> I hope this is the correct place to report problems with the GPLPV
> drivers:
> 
> The Xen setup is the following:
> - Dom0: A 2.6.18-based Xen kernel (from Debian Etch) and Xen 3.2.0
> (3.2.0-3~bpo4+2 to be precise)
> - DomU: GPLPV drivers 0.9.11-pre18 and  Windows 2003 (32 bits)
> 
> The performance with GPLPV is quite good (the speedup in network speed is
> almost ten times), but there are problems when copying huge files over the
> network using Windows Explorer:
> After about 40% some packets get lost (as tested by having a continuous
> ping
> on the virtualised host) for some seconds and Windows aborts copying the
> file. /var/log/xen/xend.log contains an error message, which correlates to
> the time of connection tear down:
> 
> ERROR (__init__:1072) Internal error handling  system.methodSignature:
> Invalid
> result signatures not supported
> 
> Operation with smaller files is reliable.
> 
> The initial setup was based on a DRBD file system, but the error could be
> reproduced on plain file storage as well. Likewise, it could be ruled out
> that the problem is SMP-specific, since it could be reproduced with a
> single
> processor system as well.
> 
> When booting without GPLPV driver support the problems disappears.
> Is this a known problem? What further information could be collected to
> pinpoint the problem?
> 

Not a known problem, but it should be reproducible. I have done some large file 
copying, but your 'huge' and my 'large' may be vastly different - how big are 
the files you are talking about?

How willing are you to run some tests for me? The xennet drivers have no limits 
on how much memory they could allocate internally for packet buffers. I've 
never seen that as a problem but it's possible that they could be running out 
of resources and not handling that situation properly. Alternatively they could 
be running windows out of resources and windows isn't handling that properly.

Can you please test and tell me if the 40% figure changes if you give your 
windows DomU much more or much less memory? I would hope that with much less 
memory it would fail much earlier...

It could also be related to gso or csum offload... do things change if you 
disable either of those?

Thanks for the feedback

James


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