Re: [PATCH 06/22] kbuild: lto: limit inlining
From: Peter Zijlstra <peterz@infradead.org>
Date: 2020-06-24 21:21:20
Also in:
linux-arch, linux-kbuild, linux-pci, lkml
On Wed, Jun 24, 2020 at 01:31:44PM -0700, Sami Tolvanen wrote:
This change limits function inlining across translation unit boundaries in order to reduce the binary size with LTO. The -import-instr-limit flag defines a size limit, as the number of LLVM IR instructions, for importing functions from other TUs. The default value is 100, and decreasing it to 5 reduces the size of a stripped arm64 defconfig vmlinux by 11%.
Is that also the right number for x86? What about the effect on performance? What did 6 do? or 4?
quoted hunk ↗ jump to hunk
Suggested-by: George Burgess IV <redacted> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- Makefile | 4 ++++ 1 file changed, 4 insertions(+)diff --git a/Makefile b/Makefile index 3a7e5e5c17b9..ee66513a5b66 100644 --- a/Makefile +++ b/Makefile@@ -894,6 +894,10 @@ else CC_FLAGS_LTO_CLANG := -flto endif CC_FLAGS_LTO_CLANG += -fvisibility=default + +# Limit inlining across translation units to reduce binary size +LD_FLAGS_LTO_CLANG := -mllvm -import-instr-limit=5 +KBUILD_LDFLAGS += $(LD_FLAGS_LTO_CLANG) endif ifdef CONFIG_LTO-- 2.27.0.212.ge8ba1cc988-goog
_______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel