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| author | Miroslav Benes <mbenes@suse.cz> | 2019-04-04 20:44:11 +0200 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2019-04-08 16:48:52 +0200 |
| commit | 43bd3a95c98e1a86b8b55d97f745c224ecff02b9 (patch) | |
| tree | 624c5f37459b9734e8cc1eddf7d6839a5943cd59 /Makefile | |
| parent | f9d138145686b52b48ccb36557d6842076e2b9dd (diff) | |
| download | lwn-43bd3a95c98e1a86b8b55d97f745c224ecff02b9.tar.gz lwn-43bd3a95c98e1a86b8b55d97f745c224ecff02b9.zip | |
kbuild: use -flive-patching when CONFIG_LIVEPATCH is enabled
GCC 9 introduces a new option, -flive-patching. It disables certain
optimizations which could make a compilation unsafe for later live
patching of the running kernel.
The option is used only if CONFIG_LIVEPATCH is enabled and $(CC)
supports it.
Performance impact of the option was measured on three different
Intel machines - two bigger NUMA boxes and one smaller UMA box. Kernel
intensive (IO, scheduling, networking) benchmarks were selected, plus a
set of HPC workloads from NAS Parallel Benchmark. The tests were done on
upstream kernel 5.0-rc8 with openSUSE Leap 15.0 userspace.
The majority of the tests is unaffected. The only significant exception
is the scheduler section which suffers 1-3% degradation.
Evaluated-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Diffstat (limited to 'Makefile')
| -rw-r--r-- | Makefile | 4 |
1 files changed, 4 insertions, 0 deletions
@@ -796,6 +796,10 @@ KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections LDFLAGS_vmlinux += --gc-sections endif +ifdef CONFIG_LIVEPATCH +KBUILD_CFLAGS += $(call cc-option, -flive-patching=inline-clone) +endif + # arch Makefile may override CC so keep this after arch Makefile is included NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) |