diff options
author | Hagen Paul Pfeifer <hagen@jauu.net> | 2015-04-21 00:27:11 +0300 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2015-04-22 09:14:41 +0300 |
commit | 3462bd2adeadc49d9e126bca3b5536a3437a902d (patch) | |
tree | f08460f362ff6a40942b45d0e7310848ea4fb46c /arch | |
parent | aac82d319148c6a84e1bf90b86d3e0ec8bf0ee38 (diff) | |
download | linux-3462bd2adeadc49d9e126bca3b5536a3437a902d.tar.xz |
x86/asm: Always inline atomics
During some code analysis I realized that atomic_add(), atomic_sub()
and friends are not necessarily inlined AND that each function
is defined multiple times:
atomic_inc: 544 duplicates
atomic_dec: 215 duplicates
atomic_dec_and_test: 107 duplicates
atomic64_inc: 38 duplicates
[...]
Each definition is exact equally, e.g.:
ffffffff813171b8 <atomic_add>:
55 push %rbp
48 89 e5 mov %rsp,%rbp
f0 01 3e lock add %edi,(%rsi)
5d pop %rbp
c3 retq
In turn each definition has one or more callsites (sure):
ffffffff81317c78: e8 3b f5 ff ff callq ffffffff813171b8 <atomic_add> [...]
ffffffff8131a062: e8 51 d1 ff ff callq ffffffff813171b8 <atomic_add> [...]
ffffffff8131a190: e8 23 d0 ff ff callq ffffffff813171b8 <atomic_add> [...]
The other way around would be to remove the static linkage - but
I prefer an enforced inlining here.
Before:
text data bss dec hex filename
81467393 19874720 20168704 121510817 73e1ba1 vmlinux.orig
After:
text data bss dec hex filename
81461323 19874720 20168704 121504747 73e03eb vmlinux.inlined
Yes, the inlining here makes the kernel even smaller! ;)
Linus further observed:
"I have this memory of having seen that before - the size
heuristics for gcc getting confused by inlining.
[...]
It might be a good idea to mark things that are basically just
wrappers around a single (or a couple of) asm instruction to be
always_inline."
Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1429565231-4609-1-git-send-email-hagen@jauu.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/include/asm/atomic.h | 16 | ||||
-rw-r--r-- | arch/x86/include/asm/atomic64_64.h | 8 |
2 files changed, 12 insertions, 12 deletions
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h index 5e5cd123fdfb..75a9ee8529f3 100644 --- a/arch/x86/include/asm/atomic.h +++ b/arch/x86/include/asm/atomic.h @@ -46,7 +46,7 @@ static inline void atomic_set(atomic_t *v, int i) * * Atomically adds @i to @v. */ -static inline void atomic_add(int i, atomic_t *v) +static __always_inline void atomic_add(int i, atomic_t *v) { asm volatile(LOCK_PREFIX "addl %1,%0" : "+m" (v->counter) @@ -60,7 +60,7 @@ static inline void atomic_add(int i, atomic_t *v) * * Atomically subtracts @i from @v. */ -static inline void atomic_sub(int i, atomic_t *v) +static __always_inline void atomic_sub(int i, atomic_t *v) { asm volatile(LOCK_PREFIX "subl %1,%0" : "+m" (v->counter) @@ -76,7 +76,7 @@ static inline void atomic_sub(int i, atomic_t *v) * true if the result is zero, or false for all * other cases. */ -static inline int atomic_sub_and_test(int i, atomic_t *v) +static __always_inline int atomic_sub_and_test(int i, atomic_t *v) { GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, "er", i, "%0", "e"); } @@ -87,7 +87,7 @@ static inline int atomic_sub_and_test(int i, atomic_t *v) * * Atomically increments @v by 1. */ -static inline void atomic_inc(atomic_t *v) +static __always_inline void atomic_inc(atomic_t *v) { asm volatile(LOCK_PREFIX "incl %0" : "+m" (v->counter)); @@ -99,7 +99,7 @@ static inline void atomic_inc(atomic_t *v) * * Atomically decrements @v by 1. */ -static inline void atomic_dec(atomic_t *v) +static __always_inline void atomic_dec(atomic_t *v) { asm volatile(LOCK_PREFIX "decl %0" : "+m" (v->counter)); @@ -113,7 +113,7 @@ static inline void atomic_dec(atomic_t *v) * returns true if the result is 0, or false for all other * cases. */ -static inline int atomic_dec_and_test(atomic_t *v) +static __always_inline int atomic_dec_and_test(atomic_t *v) { GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e"); } @@ -152,7 +152,7 @@ static inline int atomic_add_negative(int i, atomic_t *v) * * Atomically adds @i to @v and returns @i + @v */ -static inline int atomic_add_return(int i, atomic_t *v) +static __always_inline int atomic_add_return(int i, atomic_t *v) { return i + xadd(&v->counter, i); } @@ -191,7 +191,7 @@ static inline int atomic_xchg(atomic_t *v, int new) * Atomically adds @a to @v, so long as @v was not already @u. * Returns the old value of @v. */ -static inline int __atomic_add_unless(atomic_t *v, int a, int u) +static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u) { int c, old; c = atomic_read(v); diff --git a/arch/x86/include/asm/atomic64_64.h b/arch/x86/include/asm/atomic64_64.h index f8d273e18516..b965f9e03f2a 100644 --- a/arch/x86/include/asm/atomic64_64.h +++ b/arch/x86/include/asm/atomic64_64.h @@ -40,7 +40,7 @@ static inline void atomic64_set(atomic64_t *v, long i) * * Atomically adds @i to @v. */ -static inline void atomic64_add(long i, atomic64_t *v) +static __always_inline void atomic64_add(long i, atomic64_t *v) { asm volatile(LOCK_PREFIX "addq %1,%0" : "=m" (v->counter) @@ -81,7 +81,7 @@ static inline int atomic64_sub_and_test(long i, atomic64_t *v) * * Atomically increments @v by 1. */ -static inline void atomic64_inc(atomic64_t *v) +static __always_inline void atomic64_inc(atomic64_t *v) { asm volatile(LOCK_PREFIX "incq %0" : "=m" (v->counter) @@ -94,7 +94,7 @@ static inline void atomic64_inc(atomic64_t *v) * * Atomically decrements @v by 1. */ -static inline void atomic64_dec(atomic64_t *v) +static __always_inline void atomic64_dec(atomic64_t *v) { asm volatile(LOCK_PREFIX "decq %0" : "=m" (v->counter) @@ -148,7 +148,7 @@ static inline int atomic64_add_negative(long i, atomic64_t *v) * * Atomically adds @i to @v and returns @i + @v */ -static inline long atomic64_add_return(long i, atomic64_t *v) +static __always_inline long atomic64_add_return(long i, atomic64_t *v) { return i + xadd(&v->counter, i); } |