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SubjectRe: [PATCH v2] x86: page: get_order() optimization
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On Sat, 27/03/2011 at 13:33 +0200, Ingo Molnar wrote:
> Just wondering, what's the before/after 'size vmlinux' effect on a 'make
> defconfig' x86 kernel? Does the optimization make the kernel smaller as well,
> besides making it faster?

Thank you for advice. I didn't really mentioned it. So without my patch:

size vmlinux
text data bss dec hex filename
7915025 1253060 1122304 10290389 9d04d5 vmlinux

And with it:

size vmlinux
text data bss dec hex filename
7919150 1251364 1122304 10292818 9d0e52 vmlinux

Size increased. But I discovered that if I replace "inline" with
"__always_inline" in get_order(), size will be following:

size vmlinux
text data bss dec hex filename
7914481 1249252 1122304 10286037 9cf3d5 vmlinux

And this is less than with same modification in asm-general:

size vmlinux
text data bss dec hex filename
7914713 1249268 1122304 10286285 9cf4cd vmlinux

With my patch and "__always_inline" instead of just "inline" size will
be the smallest.

Signed-off-by: Maksym Planeta <mcsim.planeta@gmail.com>
---
arch/x86/include/asm/getorder.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/getorder.h
b/arch/x86/include/asm/getorder.h
index b0c6f57..6220783 100644
--- a/arch/x86/include/asm/getorder.h
+++ b/arch/x86/include/asm/getorder.h
@@ -27,7 +27,7 @@ static __always_inline int __get_order(unsigned long
size)
}

/* Pure 2^n version of get_order */
-static inline __attribute_const__ int get_order(unsigned long size)
+static __always_inline __attribute_const__ int get_order(unsigned long
size)
{
int order;
--
Thanks,

Maksym Planeta


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