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

Andrew Morton
2015-05-08T23:19:15Z

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 :-)

I like NO_INTERRUPTS. Simple, direct.