linux-kernel - Re: [PATCH 51/56] drivers/char/mem: support compiling out splice

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Message-ID: <20141116182007.GA5032@thin>
Date:	Sun, 16 Nov 2014 10:20:07 -0800
From:	Josh Triplett <josh@...htriplett.org>
To:	Pieter Smith <pieter@...sman.nl>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	open list <linux-kernel@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH 51/56] drivers/char/mem: support compiling out splice

[Please don't top-post.]

On Sun, Nov 16, 2014 at 01:18:27PM +0100, Pieter Smith wrote:
> I had a look at the numbers (see below): For a tinyconfig kernel, savings
> outside fs/splice.c are negligible. With the addition of networking
> however, net/core and net/ipv4 can be squeezed for usable savings.
> 
> Should I leave networking (and the rest) until we can come up with a
> non-icky approach outside fs/splice.c?
>
> *THE NUMBERS*
> 
> Given a tinyconfig, fs/splice.c can free up 8.2K (3.5K + 4.7K) with
> CONFIG_SYSCALL_SPLICE. The rest are not worth the effort:
>   fs/splice:
>     syscalls only: add/remove: 0/16 grow/shrink: 2/5 up/down: 114/-3693
> (-3579)
>     the remainder: add/remove: 0/24 grow/shrink: 0/4 up/down: 0/-4824
> (-4824)

Nice!

Go ahead and submit the patches for that portion, and the rest can wait
until we get compiler support for omitting structure fields.

- Josh Triplett
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