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Re: [Xen-devel] Data broken during FTP test

Hi Ian,

Thank you for reply.

Please can you provide more information about the exact xen version
used, and the test configuration. What is the nature of the corruption
introduced?

The version of Xen used RHEL5GA.

This problem has happened comparatively only by new NIC.
It is following NIC that this problem happened first.
Broadcom Corporation NetXtreme BCM5715 Gigabit Ethernet (rev a3)

The PV domain(domain_1) is created, and FTP test jobs were executed
between PV domain and FTP client(other PC).
Other PV domain(domain_2) connected with the same bridge are created.
The FTP data was broken when the network started on other created PV domains.
FTP data was broken only when it is transmitted from PV domain to FTP client.
We offer the material of environment and configuration files.

However, this problem doesn't happen because of the change in the setting.
1. SG(scatter/gather) flag off
2. 'mem=1G' is set as a boot parameter, and SG(scatter/gather) flag on.

We are guessing this problem as follows.(Data_broken_during_FTP_test.doc)

Frame information and data are collected by Scatter/Gather offload function
on the NIC side and frame is made.
The buffer data of Dom0 is liberated with ack from NIC.
Therefore, the buffer is used other forwarding.

The request of sending again is notified to guest OS when there is a request of
the TCP sending again.
However, it seems to read data from the buffer because data is maintained
in the buffer of Dom0 as for NIC and to send it again.

When the SG flag is turning off, the request of the TCP sending again is notified
and event guest OS is notified.
Therefore, FTP data is not broken because it is sent again by guest OS(domain_1).

However, the reason why this problem doesn't happen when the memory of Xen is limited is not understood.

Best Regards,

--
Takanori Kasai

Attachment: domain_2.dat
Description: Binary data

Attachment: domain_1.dat
Description: Binary data

Attachment: Data_broken_during_FTP_test.doc
Description: MS-Word document

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