Re: [PATCH] nohz1: Documentation

From: Paul E. McKenney
Date: Thu Mar 21 2013 - 11:18:46 EST

On Thu, Mar 21, 2013 at 11:16:50AM +0100, Borislav Petkov wrote:
> On Wed, Mar 20, 2013 at 07:22:59PM -0700, Paul E. McKenney wrote:
> > > > > > The "full_nohz=" boot parameter specifies which CPUs are to be
> > > > > > adaptive-ticks CPUs. For example, "full_nohz=1,6-8" says that CPUs 1,
> > > > >
> > > > > This is the first time you mention "adaptive-ticks". Probably should
> > > > > define it before just using it, even though one should be able to figure
> > > > > out what adaptive-ticks are, it does throw in a wrench when reading this
> > > > > if you have no idea what an "adaptive-tick" is.
> > > >
> > > > Good point, changed the first sentence of this paragraph to read:
> > > >
> > > > The CONFIG_NO_HZ_FULL=y Kconfig option causes the kernel to
> > > > avoid sending scheduling-clock interrupts to CPUs with a single
> > > > runnable task, and such CPUs are said to be "adaptive-ticks CPUs".
> > >
> > > Sounds good.
> Yeah,
> so I read this last night too and I have to say, very clearly written,
> even for dummies like me.

Can't say that I think of you as a dummy, but glad you liked it!

> But this "adaptive-ticks CPUs" reads kinda strange throughout the whole
> text, it feels a bit weird. And since the cmdline option is called
> "full_nohz", you might just as well call them the "full_nohz CPUs" or
> the "full_nohz subset of CPUs" for simplicity and so that you don't have
> yet another new term in the text denoting the same idea. I mean, all
> those names kinda suck and need the full definition of what adaptive
> ticking actually means anyway. :)

I am happy with either "adaptive-ticks CPUs" or "full_nohz CPUs", and
leave the choice to Frederic.

> Btw, congrats on coining a new noun: "Adaptive-tick mode may prevent
> this round-robining from happening."
> ^^^^^^^^^^^^^^

Actually, this is a generic transformation. Given an English verb,
you almost always add "ing" to create a noun. Since "round-robin" is
used as a verb, as in "The scheduler will round-robin between the two
SCHED_RR tasks", "round-robining" may be used as a noun denoting the
action corresponding to the verb "round-robin". There is no doubt
an argument as to whether this should be spelled "round-robining" or
"round-robinning", but I will leave this to those who care enough to
argue about it. ;-)

> Funny. :-)
> I spose now one can say: "The kids in the garden are round-robining on
> the carousel."
> or
> "The kernel developers are round-robined for pull requests."


> Or maybe it wasn't you who coined it after /me doing a little search. It
> looks like technical people are pushing hard for it to be committed in
> the upstream English language repository. :-)

The thing about English is that it is an open-source language, and always
has been. English is defined by its usage, and the wise dictionary-makers
try their best to keep up. (The unwise ones attempt to stop the evolution
of the English language.) Everything good and everything bad about
English stems from this property. ;-)

Thanx, Paul

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