Re: Where do we stand with the Xen patches?

[david]

On Sun, 17 May 2009, devzero@xxxxxx wrote:

> > > Aside from some whitespace issues around some Impact: lines, I
> > > don't know of any outstanding problems.  (I just pushed an updates
> > > to these branches to fix those, and fold a change to address
> > > Jesse's comment.)
> > >
> > > Please tell me if you have any further issues which prevents you
> > > from pulling these changes.  Otherwise I'd appreciate it if you
> > > pulled them soon, as we're already on -rc5, and I have more
> > > changes I'd like to prep for the next merge window.
> >
> > As in the past, my main worry is performance overhead of paravirt in
> > general.
> >
> > The patches that dont affect any native kernel fast path are
> > probably OK (but still pending final review).
> >
> > Regarding patches that do change the fastpath i'll do a round of
> > measurements of CONFIG_PARAVIRT against !CONFIG_PARAVIRT kernels,
> > and make up my mind based on that.
> >
> > You could accelerate this by sending some "perf stat" hard numbers
> > to give us an idea about where we stand today.
> >
> > 	Ingo
>
> maybe this is iust a stupid comment (please forgive, i?m no advanced kernel
> hacker), but can?t the code inserted by the patches and which changes the
> fastpath just #IFDEF`ed at the critical offsets ?  (as building a dom0 kernel is
> just another build target, isn`t it ?)

no, if dom0 is going to be widely deployed, it will be because the distros 
turn on dom0 support by default. as a result any penalties due to xen 
support will be felt by all users of those distros (even if they don't use 
xen)

David Lang
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