Re: [dpdk-stable] [PATCH v2 2/2] eal: restrict ctrl threads to startup cpu affinity

From: Thomas Monjalon <thomas@monjalon.net>
To: David Marchand <david.marchand@redhat.com>,
	"Burakov, Anatoly" <anatoly.burakov@intel.com>
Cc: stable@dpdk.org, dev@dpdk.org,
	Olivier Matz <olivier.matz@6wind.com>,
	Kevin Traynor <ktraynor@redhat.com>
Subject: Re: [dpdk-stable] [PATCH v2 2/2] eal: restrict ctrl threads to startup cpu affinity
Date: Tue, 19 Feb 2019 17:03:03 +0100	[thread overview]
Message-ID: <4081676.pH4rpHE09Y@xps> (raw)
In-Reply-To: <CAJFAV8wRz=efMb7M0d0mSSiKf6cvB8UZwKz8=LuUOK4EwCxQ5A@mail.gmail.com>

19/02/2019 12:51, David Marchand:
> On Tue, Feb 19, 2019 at 12:38 PM Burakov, Anatoly <anatoly.burakov@intel.com>
> wrote:
> > On 14-Feb-19 1:30 PM, David Marchand wrote:
> > > --- a/doc/guides/prog_guide/env_abstraction_layer.rst
> > > +++ b/doc/guides/prog_guide/env_abstraction_layer.rst
> > > +Control Thread API
> > > +~~~~~~~~~~~~~~~~~~
> > > +
> > > +It is possible to create Control Threads using the public API
> > ``rte_ctrl_thread_create()``.
> > > +Those threads can be used for management/infrastructure tasks and are
> > used internally by DPDK for multi process support and interrupt handling.
> > > +
> > > +Those threads will be scheduled on cpus part of the original process
> > cpu affinity from which the dataplane and service lcores are excluded.
> > > +
> > > +For example, on a 8 cpus system, starting a dpdk application with -l
> > 2,3 (dataplane cores), then depending on the affinity configuration which
> > can be controlled with tools like taskset (Linux) or cpuset (FreeBSD),
> > > +
> > > +- with no affinity configuration, the Control Threads will end up on
> > 0-1,4-7 cpus.
> > > +- with affinity restricted to 2-4, the Control Threads will end up on
> > cpu 4.
> > > +- with affinity restricted to 2-3, the Control Threads will end up on
> > cpu 2 (master lcore, which is the default when no cpu is available).
> >
> > You're not winning anything by foregoing the 80 char limit on
> > documentation (doxygen will still generate this correctly), but you're
> > losing in readability when working in terminal. I would prefer if you
> > didn't do those long lines :)
> 
> I don't really care, I will just wait for Thomas opinion.
> 
> > Thomas, do we want checkpatch to warn about this?

http://doc.dpdk.org/guides/contributing/documentation.html#line-length

Lines should not exceed 80 chars.
There is a tradition of being very flexible in docs.
The best is to wrap at the end of a logical group of words,
like after commas or dots. So the doc updates patches are easier to read.