Tell the world we gave up on pushing CC_OPTIMIZE_FOR_SIZE

In commit 281dc5c5ec0f ("Give up on pushing CC_OPTIMIZE_FOR_SIZE") we
already changed the actual default value, but the help-text still
suggested 'y'. Fix the help text too, for all the same reasons.

Sadly, -Os keeps on generating some very suboptimal code for certain
cases, to the point where any I$ miss upside is swamped by the downside.
The main ones are:

 - using "rep movsb" for memcpy, even on CPU's where that is
   horrendously bad for performance.

 - not honoring branch prediction information, so any I$ footprint you
   win from smaller code, you lose from less code density in the I$.

 - using divide instructions when that is very expensive.

Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/init/Kconfig b/init/Kconfig
index 7d30240e5bfef76aedc3a8eee2a7991abe0f0a18..be8b7f55312d1f0ea3cbb64c342eb5b456ea34a1 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1182,7 +1182,7 @@ config CC_OPTIMIZE_FOR_SIZE
          Enabling this option will pass "-Os" instead of "-O2" to gcc
          resulting in a smaller kernel.
 
-         If unsure, say Y.
+         If unsure, say N.
 
 config SYSCTL
        bool