Re: [PATCH v4 2/5] build: Hook the schedulers into Kconfig

From: Jonathan Creekmore <jonathan.creekmore@gmail.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>,
	Jonathan Creekmore <jonathan.creekmore@gmail.com>,
	Dario Faggioli <dario.faggioli@citrix.com>,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH v4 2/5] build: Hook the schedulers into Kconfig
Date: Sat, 09 Jan 2016 11:50:32 -0600	[thread overview]
Message-ID: <m28u3y4p7b.fsf@Nebula.lan> (raw)
In-Reply-To: <56911EAA.8030707@citrix.com>

Andrew Cooper writes:

> On 08/01/16 21:22, Jonathan Creekmore wrote:
>> +# Enable schedulers
>> +menu "Schedulers"
>> +	visible if EXPERT = "y"
>> +
>> +config SCHED_CREDIT
>> +	bool "Credit scheduler support"
>> +	default y
>> +	---help---
>> +	  The traditional credit scheduler is a general purpose scheduler.
>> +
>> +	  If unsure, say Y.
>> +
>> +config SCHED_CREDIT2
>> +	bool "Credit2 scheduler support (EXPERIMENTAL)"
>> +	default y
>> +	---help---
>> +	  The credit2 scheduler is a general purpose scheduler that is
>> +	  optimized for lower latency and higher VM density.
>> +
>> +	  If unsure, say Y.
>> +
>> +config SCHED_RTDS
>> +	bool "RTDS scheduler support (EXPERIMENTAL)"
>> +	default y
>> +	---help---
>> +	  The RTDS scheduler is a soft and firm real-time scheduler for
>> +	  multicore, targeted for embedded, automotive, graphics and gaming
>> +	  in the cloud, and general low-latency workloads.
>> +
>> +	  If unsure, say N.
>> +
>> +config SCHED_ARINC653
>> +	bool "ARINC653 scheduler support (EXPERIMENTAL)"
>> +	default y
>> +	---help---
>> +	  The ARINC653 scheduler is a hard real-time scheduler for single
>> +	  cores, targeted for avionics, drones, and medical devices.
>> +
>> +	  If unsure, say N.
>
> Sorry for not noticing this before.  The "If unsure, say $X" should
> really match the default value.
>
> On the other hand, given that we are hiding all these options behind
> CONFIG_EXPERT, I am not sure that we need "If unsure" clauses.  Anyone
> who isn't sure shouldn't have turned on CONFIG_EXPERT to start with.

I was trying to mimic language that the Linux kernel would use for
EXPERIMENTAL marked items. Given the documentation on the wiki, I think
marking those three schedulers EXPERIMENTAL is correct. Given that, I
still think that the language saying "If unsure, say N" is correct (the
thought being, the only people who should be messing with the
EXPERIMENTAL schedulers are people developing or specifically testing
them). The *only* reason I marked them default of Y is to keep backwards
compatibility with the current build.

However, if you would prefer me to remove the "If unsure" language
completely, I can do that. The text came in before the whole
CONFIG_EXPERT flag did.