misc/135178: Xen domU outgoing data transfer stall when TSO is enabled

[Mr. Olli]

>Number:         135178
>Category:       misc
>Synopsis:       Xen domU outgoing data transfer stall when TSO is enabled
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Jun 02 14:50:02 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Mr. Olli
>Release:        8-CURRENT r193225
>Organization:
>Environment:
FreeBSD template-8_CURRENT.domain 8.0-CURRENT FreeBSD 8.0-CURRENT #1 r193225: Mon Jun  1 17:18:52 CEST 2009     root at template-8_CURRENT.domain:/usr/obj/usr/src/sys/XEN  i386
>Description:
Transfering files larger than some size (presumably 2MB) via SSH with FreeBSD XEN para-virt domU stall after transfering 2112kb of data, when domU is source of transfer.

SSH transfers with the domU as target work properly.


>How-To-Repeat:
1) Enable TSO for xn0
2) transfer data (e.g. kernel file)

template-8_CURRENT# ifconfig xn0 tso
template-8_CURRENT# scp /boot/kernel/kernel dante at 10.30.1.15:/tmp
Password: 
kernel                                                                                                  46% 2112KB   1.4MB/s - stalled -^CKilled by signal 2.
template-8_CURRENT# 

>Fix:
As reported by "Anne Marcel Roorda" on freebsd-xen disable TCP Segmentation offloading solves the problem.

template-8_CURRENT# ifconfig xn0 -tso
template-8_CURRENT# scp /boot/kernel/kernel dante at 10.30.1.15:/tmp
kernel                                          100% 4510KB   4.4MB/s   00:00    
template-8_CURRENT# 




>Release-Note:
>Audit-Trail:
>Unformatted: