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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