Re: [PATCH] direct-io: Deinline submit_page_section, save 5304 bytes

From: Jeff Moyer
Date: Mon Mar 14 2016 - 10:36:18 EST

Denys Vlasenko <dvlasenk@xxxxxxxxxx> writes:

> This function compiles to 2628 bytes, 2 callsites
> text data bss dec hex filename
> 15197 16 0 15213 3b6d direct-io.o.before1
> 9655 16 0 9671 25c7 direct-io.o

And what is the consequence for performance? If you look at the git
history for this file, you'll find the commit that introduced the

commit ba253fbf6d3502c54e1ac8792e7ac8290a1f5b8d
Author: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Date: Mon Aug 1 21:38:08 2011 -0700

direct-io: inline the complete submission path

Add inlines to all the submission path functions. While this increases
code size it also gives gcc a lot of optimization opportunities
in this critical hotpath.


So you're essentially undoing that work.