From mboxrd@z Thu Jan  1 00:00:00 1970
From: Austin S Hemmelgarn <ahferroin7@gmail.com>
Subject: Re: [PATCH RFC 0/2] add nproc cgroup subsystem
Date: Mon, 02 Mar 2015 08:13:23 -0500
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To: Tejun Heo <tj@kernel.org>, Tim Hockin <thockin@hockin.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>, lizefan@huawei.com, richard@nod.at, mingo@redhat.com, Aleksa Sarai <cyphar@cyphar.com>, cgroups@vger.kernel.org, peterz@infradead.org, linux-kernel@vger.kernel.org

On 2015-02-28 11:43, Tejun Heo wrote:
> Hello, Tim.
>
> On Sat, Feb 28, 2015 at 08:38:07AM -0800, Tim Hockin wrote:
>> I know there is not much concern for legacy-system problems, but it is
>> worth adding this case - there are systems that limit PIDs for other
>> reasons, eg broken infrastructure that assumes PIDs fit in a short int,
>> hypothetically.  Given such a system, PIDs become precious and limiting
>> them per job is important.
>>
>> My main point being that there are less obvious considerations in play than
>> just memory usage.
>
> Sure, there are those cases but it'd be unwise to hinge long term
> decisions on them.  It's hard to even argue 16bit pid in legacy code
> as a significant contributing factor at this point.  At any rate, it
> seems that pid is a global resource which needs to be provisioned for
> reasonable isolation which is a good reason to consider controlling it
> via cgroups.
If 16-bit PID's aren't a concern anymore, then why do we still default 
to treating it like a 16-bit signed int (the default for 
/proc/sys/kernel/pid_max is 32768)?