Messages in this thread |  | | | Date | Thu, 13 Dec 2007 23:20:44 +0100 | | From | Adrian Bunk <> | | Subject | RFC: remove __read_mostly |
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I tried the following patch with a full x86 .config [1]:
--- a/include/asm-x86/cache.h +++ b/include/asm-x86/cache.h -#define __read_mostly __attribute__((__section__(".data.read_mostly"))) +/* #define __read_mostly __attribute__((__section__(".data.read_mostly"))) */ The result [2,3] was:
-rwxrwxr-x 1 bunk bunk 46607243 2007-12-13 19:50 vmlinux.old -rwxrwxr-x 1 bunk bunk 46598691 2007-12-13 21:55 vmlinux
It's not a surprise that the kernel can become bigger when __read_mostly gets used, especially in cases where __read_mostly prevents gcc optimizations.
My question is: Is there anywhere in the kernel a case where __read_mostly brings a measurable improvement or can it be removed?
cu Adrian
[1] mostly allyesconfig with CONFIG_MODULES=n [2] vmlinux.old is the unpatched kernel [3] gcc 4.2 was used
--
"Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed
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