From: Kirill Smelkov Date: Fri, 2 Nov 2012 11:41:01 +0000 (+0400) Subject: Tell the world we gave up on pushing CC_OPTIMIZE_FOR_SIZE X-Git-Tag: upstream/snapshot3+hdmi~5863 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3a55fb0d9fe8e2f4594329edd58c5fd6f35a99dd;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git 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 Signed-off-by: Linus Torvalds --- diff --git a/init/Kconfig b/init/Kconfig index 7d30240..be8b7f5 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