The fact that you say it works fine with X-Windows running and badly
from the console makes me think you've got a software problem
unrelated to Xen. If Xen+X-Windows works well, then it's hard to
imagine it being a problem with the USB/PCI. Does it work well at the
command line outside of Xen? If so, I'd spend time looking at the
difference between console+xen, gui+xen, console-xen etc, rather than
the USB & PCI passthrough. If it doesn't work well at the console
outside of Xen, then you know it's not a Xen problem.
-Dylan
On Fri, Jan 9, 2009 at 6:29 AM, jer jer <jeremie.garcia.trash@xxxxxxxxx> wrote:
> Hi everybody!
> I'm a pretty new XEN user (3.3) and I need your help on a weird situation.
> In fact I cannot conclude if it could be a XEN problem or not. So I hope you
> will be able to guide me.
> You will find below what my project is and as you guess ...the problem!
>
>
> OBJECTIVE :
> ===========
> - validate XEN solution for potential projects
> - setup a paravirtualized environment
> - embedd on a domU, software interacting with a USB connected desktop
> RFID reader
>
>
> ENVIRONMENT :
> =============
> - XEN 3.3
> - paravirtualized environment
> - dom0 : linux 2.6.24-19-xen (ubuntu) installed with no graphical
> interface
> - domU : linux 2.6.24-19-xen (ubuntu) installed with gnome and vncserver
> - PCI passthrough to dedicate all USB controllers to the single domU
> - domU is installed in a file-backed VBDs
>
> BASIC RESULT:
> =============
> - dom0 and domU boots well
> - PCI passthrough works
> - system is stable
> - on domU, lsusb shows the device connected
>
> USB DEVICE :
> ============
> - RFID desktop reader (STID)
> - serial communication ("/dev/ttyUSB0) 9600 8 n 2
> - very short instructions sent and received asynchronously (5 bytes) ;
> minimum system stress...
>
> EMBEDDED SOFTWARE :
> ===================
> - very basic test software that polls the device for an event
> - if event detected, send a sound instruction to the device
> - communication with the device is done via the serial dev file
> "/dev/ttyUSB0"
> - tested on non virtualized environment : no latency on execution and
> test succeeds
>
>
> PROBLEM :
> =========
> - running the soft from the console (xm console) without GUI introduces
> hudge execution latencies
> - if we connect our appliance from a remote PC via vncviewer, gnome is
> displayed and run the same soft from an Xterm makes the execution much more
> faster
> and coud almost be compared to non-virtualized environment perfs.
> - Note that I've tried to connect via SSH without and then with X
> exporting, and latencies are still noticed
> - it seems that latencies are only seen when interacting with the device
> - Finally, we do not want to embedd any window manager such as gnome/KDE
> for footprints concerns
> - soft have been written in C and JAVA but results are the same
>
> HELPPPPP:
> =========
> As you see, it is a very strange problem and I can't find out who's
> responsible for that :
> - is it a XEN problem?
> - is it a console problem?
> - is it a PCI passthrough problem?
> - does gnome/vnc introduces implicits optimizations?
>
>
> Furthermore, in order to find some clues:
> - can you confirm me that XEN 3.3 does not support USB2.0 (not really
> needed here ...)
> - I often have a system crash connecting USB mass storage devices (even
> dom0 get frozen) ; is it a known bug? I haven't found anything on forums.
> - based on what I've read (and test) I cannot use newer XEN kernels if I
> want to keep PCI passthrough working
> - are there some "best practices" to optimize USB passthrough
>
> I've process a lot of diff, compare, readings and I have to tell you I've no
> more idea to solve this silly problem. Any help is thus welcomed!!
>
> Thanks a lot for your help!
>
> Cordially,
> Jérémie
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users
>
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