From 60a3cdd0639473c79c253bc08c8ef8f882cca107 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 3 Mar 2008 12:38:52 +0100 Subject: x86: add optimized inlining add CONFIG_OPTIMIZE_INLINING=y. allow gcc to optimize the kernel image's size by uninlining functions that have been marked 'inline'. Previously gcc was forced by Linux to always-inline these functions via a gcc attribute: #define inline inline __attribute__((always_inline)) Especially when the user has already selected CONFIG_OPTIMIZE_FOR_SIZE=y this can make a huge difference in kernel image size (using a standard Fedora .config): text data bss dec hex filename 5613924 562708 3854336 10030968 990f78 vmlinux.before 5486689 562708 3854336 9903733 971e75 vmlinux.after that's a 2.3% text size reduction (!). Signed-off-by: Ingo Molnar --- arch/x86/Kconfig.debug | 13 +++++++++++++ arch/x86/configs/i386_defconfig | 1 + arch/x86/configs/x86_64_defconfig | 1 + 3 files changed, 15 insertions(+) (limited to 'arch') diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index 239fd9fba0a5..5b1979a45a1e 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -257,3 +257,16 @@ config CPA_DEBUG Do change_page_attr() self-tests every 30 seconds. endmenu + +config OPTIMIZE_INLINING + bool "Allow gcc to uninline functions marked 'inline'" + default y + help + This option determines if the kernel forces gcc to inline the functions + developers have marked 'inline'. Doing so takes away freedom from gcc to + do what it thinks is best, which is desirable for the gcc 3.x series of + compilers. The gcc 4.x series have a rewritten inlining algorithm and + disabling this option will generate a smaller kernel there. Hopefully + this algorithm is so good that allowing gcc4 to make the decision can + become the default in the future, until then this option is there to + test gcc for this. diff --git a/arch/x86/configs/i386_defconfig b/arch/x86/configs/i386_defconfig index 3df340b54e57..ad7ddaaff588 100644 --- a/arch/x86/configs/i386_defconfig +++ b/arch/x86/configs/i386_defconfig @@ -1421,6 +1421,7 @@ CONFIG_DEBUG_BUGVERBOSE=y # CONFIG_DEBUG_VM is not set # CONFIG_DEBUG_LIST is not set # CONFIG_FRAME_POINTER is not set +CONFIG_OPTIMIZE_INLINING=y # CONFIG_RCU_TORTURE_TEST is not set # CONFIG_LKDTM is not set # CONFIG_FAULT_INJECTION is not set diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig index eef98cb00c62..2d6f5b2809d2 100644 --- a/arch/x86/configs/x86_64_defconfig +++ b/arch/x86/configs/x86_64_defconfig @@ -1346,6 +1346,7 @@ CONFIG_DEBUG_BUGVERBOSE=y # CONFIG_DEBUG_VM is not set # CONFIG_DEBUG_LIST is not set # CONFIG_FRAME_POINTER is not set +CONFIG_OPTIMIZE_INLINING=y # CONFIG_RCU_TORTURE_TEST is not set # CONFIG_LKDTM is not set # CONFIG_FAULT_INJECTION is not set -- cgit v1.2.3-58-ga151