[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-users] Re: Xen is a feature

Thomas Gleixner wrote:
On Fri, 29 May 2009, George Dunlap wrote:
David Miller wrote:
I don't see Ingo's comments, whether I agree with them or not, as
an implication of Xen being niche.  Rather I see his comments as
an opposition to how Xen is implemented.
It's in his definition of "improving Linux".  Jeremy is saying that allowing
Linux to run as dom0 *is* improving Linux.  The lack of dom0 support is at
this moment making life more difficult for a huge number of Linux users who

Exactly that's the point. Adding dom0 makes life easier for a group of
users who decided to use Xen some time ago, but what Ingo wants is
technical improvement of the kernel.

There are many features which have been wildly used in the distro
world where developers tried to push support into the kernel with the
same line of arguments.

The kernel policy always was and still is to accept only those
features which have a technical benefit to the code base.

I'm just picking a few examples:

Aside of the paravirt, which seems to expand through arch/x86 like a
hydra, the new patches sprinkle "if (xen_...)" all over the
place. These extra xen dependencies are no improvement, they are a
royal pain in the ... They are sticky once they got merged simply
because the hypervisor relies on them and we need to provide
compatibility for a long time.

Wait, let's not classify something as "no improvement" when you mean "I don't need it." The fact that processors without hardware VM can run virtual machines is a non-trivial benefit for many users, and in future embedded applications, where both hvm and 64 bit capability may not justify their power requirements. And the improved PV performance over full virtualization is an improvement, even though it certainly isn't night and day.

Having replace some systems with new hardware just so I could use KVM does not make me forget that I used xen for some time, and that PV is still a savings, even with the latest hardware.

Let's stick to technical issues, and not deny that there are a number of users who really will have expanded capability. The technical points are valid, but as a former and probable future xen (CentOS) user, so are the benefits.

Bill Davidsen <davidsen@xxxxxxx>
  "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot

Xen-users mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.