Messages in this thread Patch in this message | | | From | Denys Vlasenko <> | Subject | [PATCH] asm-generic: force inlining of some atomic_long operations | Date | Thu, 4 Feb 2016 20:45:34 +0100 |
| |
Sometimes gcc mysteriously doesn't inline very small functions we expect to be inlined. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122
With this .config: http://busybox.net/~vda/kernel_config_OPTIMIZE_INLINING_and_Os, atomic_long_inc(), atomic_long_dec() and atomic_long_add() functions get deinlined about 40 times. Examples of disassembly:
<atomic_long_inc> (21 copies, 147 calls): 55 push %rbp 48 89 e5 mov %rsp,%rbp f0 48 ff 07 lock incq (%rdi) 5d pop %rbp c3 retq
<atomic_long_dec> (4 copies, 14 calls) is similar to inc.
<atomic_long_add> (11 copies, 41 calls): 55 push %rbp 48 89 e5 mov %rsp,%rbp f0 48 01 3e lock add %rdi,(%rsi) 5d pop %rbp c3 retq
This patch fixes this via s/inline/__always_inline/. Code size decrease after the patch is ~1.3k:
text data bss dec hex filename 92203657 20826112 36417536 149447305 8e86289 vmlinux 92202377 20826112 36417536 149446025 8e85d89 vmlinux4_atomiclong_after
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Graf <tgraf@suug.ch> Cc: Peter Zijlstra <peterz@infradead.org> Cc: David Rientjes <rientjes@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-kernel@vger.kernel.org --- include/asm-generic/atomic-long.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/asm-generic/atomic-long.h b/include/asm-generic/atomic-long.h index eb1973b..5e1f345 100644 --- a/include/asm-generic/atomic-long.h +++ b/include/asm-generic/atomic-long.h @@ -98,14 +98,14 @@ ATOMIC_LONG_ADD_SUB_OP(sub, _release) #define atomic_long_xchg(v, new) \ (ATOMIC_LONG_PFX(_xchg)((ATOMIC_LONG_PFX(_t) *)(v), (new))) -static inline void atomic_long_inc(atomic_long_t *l) +static __always_inline void atomic_long_inc(atomic_long_t *l) { ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; ATOMIC_LONG_PFX(_inc)(v); } -static inline void atomic_long_dec(atomic_long_t *l) +static __always_inline void atomic_long_dec(atomic_long_t *l) { ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; @@ -113,7 +113,7 @@ static inline void atomic_long_dec(atomic_long_t *l) } #define ATOMIC_LONG_OP(op) \ -static inline void \ +static __always_inline void \ atomic_long_##op(long i, atomic_long_t *l) \ { \ ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \ -- 1.8.1.4
| |