Hi there, I''m new to Xen. I''ve read thoroughly Xen design papers [1] [2] [3], but now I''m experimenting it, I have a couple of questions in order to match my practical experience with the idea of Xen design I''ve made up from the papers. So here is what I''ve understood. Please correct me if I''m wrong, it may be useful for future newcomers. There are a few questions along the text flow. Hints for other newbies: PV = para-virtualized; FV = full-virtualized. According to slide 49 in [4], Isolated Driver Domain (IDD) have only been implemented experimentaly but is not used at all the current official releases of Xen 3. Are there any plans about this? Currently, Virtual Block Devices (VBD) and Virtual (Network) Interfaces (VIF) are the most common way to provide storage and network devices within Xen PV guests. It is yet possible to assign exclusively a PCI device to any one DomU, in which case the DomU''s driver talks to the hardware through the "Safe Hardware Interface" (see figure 1 in [2]), enforced by I/O Spaces, as described in [2] section 4. How are other devices (simple serial console emulator, VGA emulator, ...) implemented in PV guests? I mean where does the console output make its way into my pty? Is it possible to emulate a full VGA console somehow? How can a PV guest display graphics, when running X for instance? Any documentation pointer would be welcome. What''s the goal of the "ioemu" keyword used in FV guest configuration? I couldn''t find any documentation about all this. My VBD seems to work both with or without it. Does this mean that Xen should use IOMMU (Intel''s VT-d) for this device, if present? Or does it mean it should use QEMU as backend? Again, any documentation pointer will be welcome. What''s the benefit of using QEMU backend for a disk, instead of using a VBD? BTW, I know that QEMU can emulate multiple ISA or PCI network adapters, is it possible to use them as for FV guests? What would be the benefit over a VIF? BTW, are there any chipset that currently provide VT-d? If yes, according to [2] section 8, this shouldn''t be a big deal to implement it in Xen, so is it supported in Xen 3? Thank you. Best regards, [1] http://www.cl.cam.ac.uk/netos/papers/2003-xensosp.pdf [2] http://www.cl.cam.ac.uk/netos/papers/2004-oasis-ngio.pdf [3] http://www.intel.com/technology/itj/2006/v10i3/3-xen/4-extending-with-intel-vt.htm [4] http://www.cl.cam.ac.uk/netos/papers/2005-xen-ols.ppt -- Jeremie Le Hen < jeremie at le-hen dot org >< ttz at chchile dot org > _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Javier Guerra
2008-Jan-14 22:33 UTC
Re: [Xen-users] A few newbie questions about Xen devices
On 1/14/08, Jeremie Le Hen <jeremie@le-hen.org> wrote:> What''s the benefit of using QEMU backend for a disk, instead of using > a VBD? BTW, I know that QEMU can emulate multiple ISA or PCI network > adapters, is it possible to use them as for FV guests? What would be > the benefit over a VIF?i don''t think qemu is used at all for PV guests. -- Javier _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Jeremie Le Hen
2008-Jan-14 22:38 UTC
Re: [Xen-users] A few newbie questions about Xen devices
On Mon, Jan 14, 2008 at 05:33:49PM -0500, Javier Guerra wrote:> On 1/14/08, Jeremie Le Hen <jeremie@le-hen.org> wrote: > > What''s the benefit of using QEMU backend for a disk, instead of using > > a VBD? BTW, I know that QEMU can emulate multiple ISA or PCI network > > adapters, is it possible to use them as for FV guests? What would be > > the benefit over a VIF? > > i don''t think qemu is used at all for PV guests.You are right and I didn''t intend to mean this. I''m sorry if I have not been clear enough. -- Jeremie Le Hen < jeremie at le-hen dot org >< ttz at chchile dot org > _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
A question to the group: If there are two (or more) DomU''s running under Xen, is it possible for them to communicate with each other via some sort of virtual network configuration that would be extremely fast because there''s no physical networking involved? ---Kayvan _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Do you mean xen-bridge? You could configure a virtual switch (aka bridge) and attach each xen DomU to the bridge. Then they can communicate via IP through the private Ethernet interface. Not sure what the performance metrics are for xen-bridge. -Matt On Jan 14, 2008, at 6:16 PM, Kayvan Sylvan wrote:> A question to the group: > > If there are two (or more) DomU''s running under Xen, is it possible > for > them to communicate with each other via some sort of virtual network > configuration that would be extremely fast because there''s no physical > networking involved? > > ---Kayvan > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi All
I am running centos5 native xen in x4100 M 8 core with 16GB . When I try
to do live migration to another host. I''ll get following error
message.
File "/usr/lib64/python2.4/site-packages/xen/xend/XendCheckpoint.py",
line
339, in forkHelper
raise XendError("%s failed" % string.join(cmd))
XendError: /usr/lib64/xen/bin/xc_restore 15 1 1 2 0 0 0 failed
I am running x64 kernel which is 2.6.18-53.1.4.el5xen #1 SMP on both hosts.
Any idea?
Thanks in advance
Thave
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XenoCrateS
2008-Jan-15 06:31 UTC
Re: [Xen-users] A few newbie questions about Xen devices - virtual networking
practically, the earlier answer about using a bridge would suffice. But if you are looking at MPI kind of loads or aiming for better performance, i suggest you take a look at the Xen-Socket proposal (possibly a code exists out there too), that was presented in the Xen Summit April 2007 by a researcher from IBM . --It had excellent results compared to a standard tcp/ip communication mechanism between two DomUs in the same physical host. Jeremie Le Hen wrote:> Hi there, > > I''m new to Xen. I''ve read thoroughly Xen design papers [1] [2] [3], but > now I''m experimenting it, I have a couple of questions in order to match > my practical experience with the idea of Xen design I''ve made up from > the papers. > > So here is what I''ve understood. Please correct me if I''m wrong, it > may be useful for future newcomers. There are a few questions along the > text flow. > > Hints for other newbies: PV = para-virtualized; FV = full-virtualized. > > According to slide 49 in [4], Isolated Driver Domain (IDD) have only > been implemented experimentaly but is not used at all the current > official releases of Xen 3. Are there any plans about this? > > Currently, Virtual Block Devices (VBD) and Virtual (Network) Interfaces > (VIF) are the most common way to provide storage and network devices > within Xen PV guests. It is yet possible to assign exclusively a PCI > device to any one DomU, in which case the DomU''s driver talks to the > hardware through the "Safe Hardware Interface" (see figure 1 in [2]), > enforced by I/O Spaces, as described in [2] section 4. > > How are other devices (simple serial console emulator, VGA emulator, > ...) implemented in PV guests? I mean where does the console output > make its way into my pty? Is it possible to emulate a full VGA console > somehow? How can a PV guest display graphics, when running X for > instance? Any documentation pointer would be welcome. > > What''s the goal of the "ioemu" keyword used in FV guest configuration? > I couldn''t find any documentation about all this. My VBD seems to work > both with or without it. Does this mean that Xen should use IOMMU > (Intel''s VT-d) for this device, if present? Or does it mean it should > use QEMU as backend? Again, any documentation pointer will be welcome. > > What''s the benefit of using QEMU backend for a disk, instead of using > a VBD? BTW, I know that QEMU can emulate multiple ISA or PCI network > adapters, is it possible to use them as for FV guests? What would be > the benefit over a VIF? > > BTW, are there any chipset that currently provide VT-d? If yes, > according to [2] section 8, this shouldn''t be a big deal to implement it > in Xen, so is it supported in Xen 3? > > Thank you. > Best regards, > > [1] http://www.cl.cam.ac.uk/netos/papers/2003-xensosp.pdf > [2] http://www.cl.cam.ac.uk/netos/papers/2004-oasis-ngio.pdf > [3] http://www.intel.com/technology/itj/2006/v10i3/3-xen/4-extending-with-intel-vt.htm > > [4] http://www.cl.cam.ac.uk/netos/papers/2005-xen-ols.ppt >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Jeremie Le Hen
2008-Jan-15 08:27 UTC
Re: [Xen-users] A few newbie questions about Xen devices - virtual networking
Hi, On Mon, Jan 14, 2008 at 10:31:35PM -0800, XenoCrateS wrote:> practically, the earlier answer about using a bridge would suffice. But if > you are looking at MPI kind of loads or aiming for better performance, i > suggest you take a look at the Xen-Socket proposal (possibly a code exists > out there too), that was presented in the Xen Summit April 2007 by a > researcher from IBM . > --It had excellent results compared to a standard tcp/ip communication > mechanism between two DomUs in the same physical host.Thank you for you answer, but my thread has been hijacked by "Virtual networking?" from Kayvan Sylvan and I suppose your reply is more related to his topic than mine. Another reason why creating a new thread by clicking on "Reply-to" is not a good idea. Thank you. Best regards, -- Jeremie Le Hen < jeremie at le-hen dot org >< ttz at chchile dot org > _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users