Re: [PATCH 0/6] support "dataplane" mode for nohz_full

Mike Galbraith
2015-05-09T07:19:51Z

On Sat, 2015-05-09 at 09:05 +0200, Ingo Molnar wrote:
> * Andrew Morton <akpm@linux-foundation.org> wrote:
>
> > On Fri, 8 May 2015 19:11:10 -0400 Chris Metcalf <cmetcalf@ezchip.com> wrote:
> >
> > > On 5/8/2015 5:22 PM, Steven Rostedt wrote:
> > > > On Fri, 8 May 2015 14:18:24 -0700
> > > > Andrew Morton <akpm@linux-foundation.org> wrote:
> > > >
> > > >> On Fri, 8 May 2015 13:58:41 -0400 Chris Metcalf <cmetcalf@ezchip.com> wrote:
> > > >>
> > > >>> A prctl() option (PR_SET_DATAPLANE) is added
> > > >> Dumb question: what does the term "dataplane" mean in this context? I
> > > >> can't see the relationship between those words and what this patch
> > > >> does.
> > > > I was thinking the same thing. I haven't gotten around to searching
> > > > DATAPLANE yet.
> > > >
> > > > I would assume we want a name that is more meaningful for what is
> > > > happening.
> > >
> > > The text in the commit message and the 0/6 cover letter do try to explain
> > > the concept. The terminology comes, I think, from networking line cards,
> > > where the "dataplane" is the part of the application that handles all the
> > > fast path processing of network packets, and the "control plane" is the part
> > > that handles routing updates, etc., generally slow-path stuff. I've probably
> > > just been using the terms so long they seem normal to me.
> > >
> > > That said, what would be clearer? NO_HZ_STRICT as a superset of
> > > NO_HZ_FULL? Or move away from the NO_HZ terminology a bit; after all,
> > > we're talking about no interrupts of any kind, and maybe NO_HZ is too
> > > limited in scope? So, NO_INTERRUPTS? USERSPACE_ONLY? Or look
> > > to vendors who ship bare-metal runtimes and call it BARE_METAL?
> > > Borrow the Tilera marketing name and call it ZERO_OVERHEAD?
> > >
> > > Maybe BARE_METAL seems most plausible -- after DATAPLANE, to me,
> > > of course :-)
>
> 'baremetal' has uses in virtualization speak, so I think that would be
> confusing.
>
> > I like NO_INTERRUPTS. Simple, direct.
>
> NO_HZ_PURE?

Hm, coke light, coke zero... OS_LIGHT and OS_ZERO?

-Mike