linux-kernel - Re: [PATCH] Add possibility to set /dev/tty number

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Message-ID: <568D0BB6.30606@gmail.com>
Date:	Wed, 6 Jan 2016 07:42:30 -0500
From:	"Austin S. Hemmelgarn" <ahferroin7@...il.com>
To:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	Pierre Paul MINGOT <mingot.pierre@...il.com>, jslaby@...e.cz,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Add possibility to set /dev/tty number

On 2016-01-05 15:47, One Thousand Gnomes wrote:
>> This means that not including the VT subsystem resulted in a 128k
>> reduction in runtime footprint, and having only half the number of VT's
>> resulted in a 52k reduction.  Assuming a linear correlation between the
>> number of VT's and the runtime footprint of the subsystem, that means
>> the subsystem itself incurs 26k of overhead, and each VT incurs
>> approximately 1.6k of overhead.
>
> Doesn't seem an unreasonable value - so yes you've made an argument for
> dynamically allocating the vt structures when they are first referenced.
No, I've made an argument for finding some way to reduce the runtime 
impact of the VT subsystem.  Dynamic allocation is one way to do that, 
but not the only way.

In fact, there already appears to be some degree of allocation on demand 
for VT's (otherwise deallocvt has no point), just not for everything 
associated with the VT.  I'd be willing to bet that almost everything 
that reasonably can be dynamically allocated already is, there is a bare 
minimum required for even a virtual device after all.
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