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Let's step back a bit

Let's step back a bit

Posted Jun 3, 2009 20:13 UTC (Wed) by ncm (subscriber, #165)
In reply to: Let's step back a bit by Thue
Parent article: Xen again

Does it really matter any more whether a new release of Xen requires hardware virtualization support? Doesn't all the current hardware where people want to run Xen have such support already? This seems akin to compilers supporting funny x86 memory models long after everybody already had a 386. (There were lots of 286s still around, but their owners weren't buying new software.) How many of these 500,000 servers running Xen can't run KVM? And aren't those on a schedule to be retired, for other reasons (e.g. power consumption, increasing failure rate, etc.) soon?


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Let's step back a bit

Posted Jun 4, 2009 12:56 UTC (Thu) by gwolf (subscriber, #14632) [Link]

> How many of these 500,000 servers running Xen can't run KVM? And aren't those on a schedule to be retired, for other reasons (e.g. power consumption, increasing failure rate, etc.) soon?

When I bought my laptop, January 2008, I shopped explicitly for one with virtualization capability. However, for a long time I just was not able to use it as such - Because of the lack of support in Xen for core features I want a laptop to support, such as ACPI (which is mainly useful for laptops, granted, but that could be very well used everywhere, leading to sensible power savings). Virtualization does not only work at the server farm, it can also be very useful at desktops.

Let's step back a bit

Posted Jun 4, 2009 15:42 UTC (Thu) by TomMD (guest, #56998) [Link]

> Virtualization does not only work at the server farm, it can also be very useful at desktops.

YES! And its not just for x86 anymore, but there are architectures that don't have VT or SVM hackery and are perfectly viable users of Xen. I'd love to run Xen on the (ARM based) beagle board or a BB based laptop.

Let's step back a bit

Posted Jun 4, 2009 20:29 UTC (Thu) by drag (subscriber, #31333) [Link]

the VT and SVM cpu extensions are only needed for X86 platform because the X68 ISA design is such a huge pile of shit.

KVM works fine on other architectures (like PowerPC), so that is all a bit of a red herring.

For x86 systems that donnot have VT/SVM you can use Kqemu and get similar functionality and speed.

Let's step back a bit

Posted Jun 9, 2009 2:11 UTC (Tue) by xyzzy (subscriber, #1984) [Link]

I migrated my Xen DomUs to kqemu VMs a year ago. I didn't rigourously benchmark but the performance drop was noticeable -- I went from being able to fill 100mbps, to not being able to fill even half of it. And this was with wget and apache and static files, so mostly an I/O performance issue.

Let's step back a bit

Posted Jun 9, 2009 7:50 UTC (Tue) by paulj (subscriber, #341) [Link]

Kqemu is long unmaintained. The Qemu developers are discussing ripping it out. Kqemu guest-kernel-space is very buggy and nearly always unuseable. So any deployment of Kqemu will run guest kernel under emulation, which obviously leads to very poor performance for all applications except those which are near-completely userspace CPU bound.

Let's step back a bit

Posted Jun 7, 2009 10:41 UTC (Sun) by djao (guest, #4263) [Link]

When I bought my laptop, January 2008, I shopped explicitly for one with virtualization capability. However, for a long time I just was not able to use it as such - Because of the lack of support in Xen for core features I want a laptop to support, such as ACPI
This is a fatal flaw in Xen, sure, but I don't understand why it would have stopped you from using KVM. You mention that you specifically bought a laptop with support for hardware virtualization, and KVM works fine with ACPI or any other core laptop feature, since KVM is just Linux.

I bought my laptop in April 2008 and I've been using it with KVM almost from day one. Everything works great, including ACPI.

Let's step back a bit

Posted Jun 4, 2009 13:28 UTC (Thu) by ESRI (guest, #52806) [Link]

I know we have a LOT of Dell PE 2850's and newer still with a lot of life and horsepower in them... perfect for running Xen, but not at all good for running KVM.


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