Re: [PATCH v3 1/4] xen: add real time scheduler rtds

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Mon, Sep 22, 2014 at 07:26:28PM +0200, Dario Faggioli wrote:
> On ven, 2014-09-19 at 12:44 -0400, Konrad Rzeszutek Wilk wrote:
> > On Thu, Sep 18, 2014 at 05:08:45PM +0100, George Dunlap wrote:
> 
> > > deadline, and then address the things I'm bringing up here?  Or would it be
> > > better to wait until all the issues are sorted and then check it in (even if
> > > it's after the deadline)?
> > 
> > We can check it in after the deadline - and have those issues resolved.
> > 
> FWIW, I think the series looks good now, and in fact I sent in my
> Reviewed-by for all of it.
> 
> > I am basing this on the assumption that:
> >  - The risks of regressions to the rest of schedulers is nill (as this is all
> >    new codepaths (as this is all
> >  - The risks of regressions to the rest of the code-base is nill (as this is all
> >    new).
> >  - The resolution of the 'couple of things' are not going to lead to more
> >    'couple of things' and lead to re-design.
> >
> This is all true, IMO.
> 
> > The common code that is touched does not look scary to me. And both of the
> > scheduler maintainers -  you and Dariof are OK with the design and the patchset
> > (minus the 'couple of things').
> > 
> Exactly.
> 
> > Are we aim to have this be experimental for Xen 4.5 or do we want this
> > to be on the 'stable' ?
> >
> Not sure. What I'm sure about is that
> 1) the interface needs to change a bit, to include support for the
>    per-vcpu parameters setting (although, that can happen in a
>    backward compatible way, i.e., not touching or altering neither the
>    look nor the semantic or the interface we'll be checking in if we
>    take v4)
> 2) there is _a_lot_ to gain, from a performance point of view, and Meng
>    already agreed on continuing working toward that, after 4.5
> 
> Having it in is, IMO, important, especially for the new
> embedded/mobile/automotive uses of Xen we're seeing in these days (in
> fact, I think GlobalLogic is using RT-Xen already, so the upstreaming of
> this scheduler would be quite useful at least to them [correct me if I'm
> wrong]).
> 
> However, given 2 above, if we mark it as stable, we risk that people
> (mostly people not yet involved into Xen development and not on this
> mailing list) would try it, run into non-optimal performance, and get
> upset/angry. For that reason, I think I'd go for 'experimental for 4.5'.

OK, will make sure that it is label as such in the release notes/Wiki.

> 
> Regards,
> Dario
> 
> -- 
> <<This happens because I choose it to happen!>> (Raistlin Majere)
> -----------------------------------------------------------------
> Dario Faggioli, Ph.D, http://about.me/dario.faggioli
> Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
>