From 3a55fb0d9fe8e2f4594329edd58c5fd6f35a99dd Mon Sep 17 00:00:00 2001
From: Kirill Smelkov <kirr@mns.spb.ru>
Date: Fri, 2 Nov 2012 15:41:01 +0400
Subject: [PATCH] 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>
---
init/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/init/Kconfig b/init/Kconfig
index 7d30240e5bfef..be8b7f55312d1 100644
--- 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
--
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