Xen users - Dec 2011 - [GPLPV] TCP-stack leaks unpaged memory pool on Windows 2008 Standard

Hi,

recently I''ve migrated our fileserver VM to a new hardware. Previously
using the slow Qemu-emulation (due to some issues with an older GPLPV version),
I decided to install the newest one. It worked fine, until about 3 days later:
the whole system came to an halt, because critical kernel services
couldn''t allocate any more unpaged memory. After destroy/create it
worked again - about two days. So to keep it usable, I reboot the VM every other
day.

I''ve monitored the "unpaged memory pool" of the Windows
kernel. Luckily every allocation needs an "tag" to be clearly
identified, so finding the responsible driver was quite easy: tcpip.sys (tag:
"tcDN")

Now, that''s a pretty basic service which usually never causes any
trouble. Strangely, it continuously allocated memory from the aforementioned
pool but never frees it, until the pool''s exhausted and kernel service
after service fails until only the mouse movement keeps functioning.

So I suspected some misconfiguration of the network. As the only thing
I''ve changed there was using the XenNet driver and I''ve read
something about issues with checksum offloading, I''ve tried various
settings. Without avail.

Finally, I''ve deactivated the GPLPV drivers using the
"NOGPLPV" kernel argument - since then it runs with the Qemu-devices
again and the pool, or tcp/ip-driver, behaves normally until now.

Has anyone experienced something like this? - Unfortunately I''ve found
nothing on the ''net regarding this issue. Only some pages which address
debugging/analyzing self-programmed drivers regarding memory leaks.

My setup is as follows:

Hardware:
        Dual-Xeon E5620 Quad-Core
        24 GByte RAM
        LSI RAID controller with about 6TByte storage
        Intel 82567LM-2 and 82574L Ethernet

Xen:
        Xen 4.1.1 (vanilla, self-compiled)

Dom0:
        Ubuntu 10.04LTS
        Vanilla, self-compiled 3.0.4 PV-OPS Linux kernel
        self-compiled DRBD 8.3.11 kernel module & utilities
        all VM storage backends on DRBD, stacked upon LVM

DomU:
        Windows Server 2008 Standard (32bit)
        4 Cores (exclusive)
        4 GByte RAM
        GPLPV: gplpv_Vista2008x32_0.11.0.308.msi
        1 Ethernet device, bridged with physical


I''d be happy for any suggestion. If there''s any information
you need not included above, feel free to ask. I want my 90MByte/s network
bandwidth back. ;)

Kind regards / Mit freundlichen Grüßen
Björn Schneider, MSc.
IT-Administration

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