linux-kernel - Re: [PATCH 1/2] sched: make nr_running() return "unsigned int"

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Message-ID: <20200312170942.GA7151@avx2>
Date:   Thu, 12 Mar 2020 20:09:42 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] sched: make nr_running() return "unsigned int"

On Thu, Mar 12, 2020 at 11:44:27AM +0100, Peter Zijlstra wrote:
> On Thu, Mar 12, 2020 at 12:06:08AM +0300, Alexey Dobriyan wrote:
> > I don't anyone have been crazy enough to spawn 2^32 threads.
> > It'd require absurd amounts of physical memory.
> 
> And we're going to 5 level page-tables because 48 bits physical isn't
> enough. 57 bits of physical is plenty space to spawn that many tasks and
> still have some left over.
> 
> Now 32 bit tasks is indeed insane, but memory isn't the problem. The
> actual limit is the pid-space, which is 30 bits.

Indeed, pid space limit is even better!