linux-kernel - [PATCH 1/1] init/Kconfig: improve CC_OPTIMIZE_FOR

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Message-Id: <1398341254-4626-2-git-send-email-michael.opdenacker@free-electrons.com>
Date:	Thu, 24 Apr 2014 14:07:34 +0200
From:	Michael Opdenacker <michael.opdenacker@...e-electrons.com>
To:	akpm@...ux-foundation.org
Cc:	paulmck@...ux.vnet.ibm.com, fweisbec@...il.com,
	josh@...htriplett.org, eparis@...hat.com,
	paul.gortmaker@...driver.com, vapier@...too.org,
	kyungsik.lee@....com, jslaby@...e.cz, dwight.engen@...cle.com,
	pefoley2@...oley.com, linux-kernel@...r.kernel.org,
	Michael Opdenacker <michael.opdenacker@...e-electrons.com>
Subject: [PATCH 1/1] init/Kconfig: improve CC_OPTIMIZE_FOR_SIZE documentation

Signed-off-by: Michael Opdenacker <michael.opdenacker@...e-electrons.com>
---
 init/Kconfig | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/init/Kconfig b/init/Kconfig
index 9d3585bb2a7a..b6394a9ddc38 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1251,7 +1251,19 @@ config CC_OPTIMIZE_FOR_SIZE
 	bool "Optimize for size"
 	help
 	  Enabling this option will pass "-Os" instead of "-O2" to gcc
-	  resulting in a smaller kernel.
+	  resulting in a smaller but slower kernel.
+
+	  This option can be useful in very small systems where every
+	  byte counts.
+
+	  A smaller kernel will also be slightly faster to load and start.
+	  However, experiments have shown that such early speedups are
+	  quickly offset by the slower kernel speed. Unless you are running
+	  a very simple user space, the total boot time should be degraded
+	  by this option.
+
+	  Anyway, kernel code will be slower to execute and overall system
+  	  performance will be degraded.
 
 	  If unsure, say N.
 
-- 
1.8.3.2

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