[Xen-bugs] [Bug 1301] Windows and Linux connection using PV Drivers crashes (bridge)

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http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1301





------- Comment #11 from james.harper@xxxxxxxxxxxxxxxx  2008-07-21 06:03 -------
> After disabling checksum offload seens to be working fine now! It`s 
> transfering
> fast but when I want to transfer files with size lasrge than 700mb the 
> transfer
> time can not estimate correctly.

Is the estimate correct when you use the qemu drivers?

In doing some testing I have noticed that sometimes the xennet drivers perform
badly, like 1/10th of the normal performance. I think something is happening
that is causing packets to be corrupted or dropped, causing tcp to go into slow
restart. On a 10 second test this could have a big impact if it happens a few
times. Of course the rings filling up would cause this too.

> Can I help you with more information to detect why checksum offload is not
> working properly?

If you could do a packet trace (I recommend wireshark for this) with GSO
disabled and CSUM offload enabled (eg your failing configuration) and confirm
to me that packets are all <1500/1514 bytes it would be useful. I'm wondering
if GSO is staying enabled even if you disabled it. A packet much larger than
1500 bytes would indicate this. Disabling csum offload should make sure it is
never enabled so you may be masking the problem by disabling that.

Otherwise, I really need to see the packet that is killing samba... preferably
on the Linux side of things... that's going to be tricky to get though.

I might put some ASSERT statements in the code to detect for things that
shouldn't happen and see if they get tripped up....


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