Re: [RFC PATCH 25/35] Add Xen time abstractions

Chris Wright
2006-05-09T23:10:50Z

* Ingo Oeser (ioe-lkml@rameria.de) wrote:
> On Tuesday, 9. May 2006 23:50, Andi Kleen wrote:
> > On Tuesday 09 May 2006 09:00, Chris Wright wrote:
> > > Add support for Xen time abstractions. To avoid expensive traps into
> > > the hypervisor, the passage of time is extrapolated from the local TSC
> > > and a set of timestamps and scaling factors exported to the guest via
> > > shared memory. Xen also provides a periodic interrupt facility which
> > > is used to drive updates of xtime and jiffies, and perform the usual
> > > process accounting and profiling.
> >
> > There is far too much code duplication in there. I think you need to
> > refactor the main time.c a bit first and strip that down.
> >
> > Also you can drop all the __x86_64__ support for now.
>
> Isn't time and timer handling a moving target anyway?
> The refactoring will be done by the timer people in a completly different
> manner anyway.
>
> Are you sure, you want to disturb these efforts by requiring another
> refactoring here?

Yes. Otherwise we end up with either duplicated code if the moving
target winds up not moving, or outdated code if it does. I agree with
Andi. It's on the todo list to refactor, but I wanted to get the
patches out even though it's a work in progress.

thanks,
-chris