diff options
| author | Rong Xu <xur@google.com> | 2024-11-02 10:51:13 -0700 |
|---|---|---|
| committer | Masahiro Yamada <masahiroy@kernel.org> | 2024-11-27 09:38:27 +0900 |
| commit | 2fd65f7afd5a73b685a1651cb651ade120b53e15 (patch) | |
| tree | e086e6e6453d4353c330caecfc3e39f503c801df | |
| parent | 0847420f5e499a7ab518942fff71482179290163 (diff) | |
AutoFDO: Enable machine function split optimization for AutoFDO
Enable the machine function split optimization for AutoFDO in Clang.
Machine function split (MFS) is a pass in the Clang compiler that
splits a function into hot and cold parts. The linker groups all
cold blocks across functions together. This decreases hot code
fragmentation and improves iCache and iTLB utilization.
MFS requires a profile so this is enabled only for the AutoFDO builds.
Co-developed-by: Han Shen <shenhan@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Yabin Cui <yabinc@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
| -rw-r--r-- | include/asm-generic/vmlinux.lds.h | 7 | ||||
| -rw-r--r-- | scripts/Makefile.autofdo | 2 |
2 files changed, 8 insertions, 1 deletions
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index bd64fdedabd2..8a0bb3946cf0 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -556,6 +556,11 @@ defined(CONFIG_AUTOFDO_CLANG) __cpuidle_text_end = .; \ __noinstr_text_end = .; +#define TEXT_SPLIT \ + __split_text_start = .; \ + *(.text.split .text.split.[0-9a-zA-Z_]*) \ + __split_text_end = .; + #define TEXT_UNLIKELY \ __unlikely_text_start = .; \ *(.text.unlikely .text.unlikely.*) \ @@ -582,6 +587,7 @@ defined(CONFIG_AUTOFDO_CLANG) ALIGN_FUNCTION(); \ *(.text.asan.* .text.tsan.*) \ *(.text.unknown .text.unknown.*) \ + TEXT_SPLIT \ TEXT_UNLIKELY \ . = ALIGN(PAGE_SIZE); \ TEXT_HOT \ @@ -589,7 +595,6 @@ defined(CONFIG_AUTOFDO_CLANG) NOINSTR_TEXT \ *(.ref.text) - /* sched.text is aling to function alignment to secure we have same * address even at second ld pass when generating System.map */ #define SCHED_TEXT \ diff --git a/scripts/Makefile.autofdo b/scripts/Makefile.autofdo index 6155d6fc4ca7..1caf2457e585 100644 --- a/scripts/Makefile.autofdo +++ b/scripts/Makefile.autofdo @@ -10,6 +10,7 @@ endif ifdef CLANG_AUTOFDO_PROFILE CFLAGS_AUTOFDO_CLANG += -fprofile-sample-use=$(CLANG_AUTOFDO_PROFILE) -ffunction-sections + CFLAGS_AUTOFDO_CLANG += -fsplit-machine-functions endif ifdef CONFIG_LTO_CLANG_THIN @@ -17,6 +18,7 @@ ifdef CONFIG_LTO_CLANG_THIN KBUILD_LDFLAGS += --lto-sample-profile=$(CLANG_AUTOFDO_PROFILE) endif KBUILD_LDFLAGS += --mllvm=-enable-fs-discriminator=true --mllvm=-improved-fs-discriminator=true -plugin-opt=thinlto + KBUILD_LDFLAGS += -plugin-opt=-split-machine-functions endif export CFLAGS_AUTOFDO_CLANG |