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authorLinus Torvalds <torvalds@linux-foundation.org>2011-05-22 14:30:36 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-22 14:30:36 -0700
commit281dc5c5ec0fb299514567cbc358562649c1af95 (patch)
tree2ecb019795e99147ce8d90b5e97c2bc3051f7855 /init
parent71a8638480eb8fb6cfabe2ee9ca3fbc6e3453a14 (diff)
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Give up on pushing CC_OPTIMIZE_FOR_SIZE
I still happen to believe that I$ miss costs are a major thing, but sadly, -Os doesn't seem to be the solution. With or without it, gcc will miss some obvious code size improvements, and with it enabled gcc will sometimes make choices that aren't good even with high I$ miss ratios. For example, with -Os, gcc on x86 will turn a 20-byte constant memcpy into a "rep movsl". While I sincerely hope that x86 CPU's will some day do a good job at that, they certainly don't do it yet, and the cost is higher than a L1 I$ miss would be. Some day I hope we can re-enable this. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig1
1 files changed, 0 insertions, 1 deletions
diff --git a/init/Kconfig b/init/Kconfig
index 4986ecc49e6..ffcdad793f1 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -908,7 +908,6 @@ endif
config CC_OPTIMIZE_FOR_SIZE
bool "Optimize for size"
- default y
help
Enabling this option will pass "-Os" instead of "-O2" to gcc
resulting in a smaller kernel.