linux-kernel - Re: [PATCH] direct-io: Deinline dio_zero

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Message-ID: <CAK1hOcOLJ_BHwJv-=ABrf9Rpycm+ppTA-DpOxF+kKbF-35BgYg@mail.gmail.com>
Date:	Sun, 13 Mar 2016 22:36:08 +0100
From:	Denys Vlasenko <vda.linux@...glemail.com>
To:	Denys Vlasenko <dvlasenk@...hat.com>
Cc:	Al Viro <viro@...iv.linux.org.uk>, Jens Axboe <axboe@...com>,
	Christoph Hellwig <hch@....de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] direct-io: Deinline dio_zero_block, save 2684 bytes

On Sun, Mar 13, 2016 at 10:00 PM, Denys Vlasenko <dvlasenk@...hat.com> wrote:
> This function compiles to 2684 bytes, 2 callsites
>
>    text    data     bss     dec     hex filename
>    9655      16       0    9671    25c7 direct-io.o.before2
>    9559      16       0    9575    2567 direct-io.o

Al, you undoubtedly noticed the discrepancy between
"save 2684 bytes" claim in the commit description
and the above data, which shows no such thing.

Sorry, I was too quick to send the mail to notice it :(

Further investigation had shown that it's my particular version of gcc
deciding to deinline the function even before the patch.
Other version of gcc, on a different machine was running
large inlining search script, did not do that, and saw the 2684 bytes
of savings.

tl;dr: the patch is correct, my "size" printout wasn't.