diff options
| author | Eric Dumazet <[email protected]> | 2009-07-03 13:23:02 +0200 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2009-07-03 14:42:59 +0200 |
| commit | 67d7178f8fc64b7f68d7dd8a1b21dfa0d42c220c (patch) | |
| tree | d14adbf73d928b9c954d8ade1a3df8c61183fd95 | |
| parent | 8e049ef054f1cc765f05f13e1396bb9a17c19e66 (diff) | |
x86: atomic64: Improve atomic64_read()
Optimize atomic64_read() as a special open-coded
cmpxchg8b variant. This generates nicer code:
arch/x86/lib/atomic64_32.o:
text data bss dec hex filename
435 0 0 435 1b3 atomic64_32.o.before
431 0 0 431 1af atomic64_32.o.after
md5:
bd8ab95e69c93518578bfaf0ea3be4d9 atomic64_32.o.before.asm
2bdfd4bd1f6b7b61b7fc127aef90ce3b atomic64_32.o.after.asm
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: David Howells <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Arnd Bergmann <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | arch/x86/lib/atomic64_32.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/arch/x86/lib/atomic64_32.c b/arch/x86/lib/atomic64_32.c index fd28fd3fb742..cd11803f9448 100644 --- a/arch/x86/lib/atomic64_32.c +++ b/arch/x86/lib/atomic64_32.c @@ -62,9 +62,17 @@ void atomic64_set(atomic64_t *ptr, u64 new_val) */ u64 atomic64_read(atomic64_t *ptr) { - u64 old = 1LL << 32; + u64 res; - return cmpxchg8b(&ptr->counter, old, old); + asm volatile( + "mov %%ebx, %%eax\n\t" + "mov %%ecx, %%edx\n\t" + LOCK_PREFIX "cmpxchg8b %1\n" + : "+A" (res) + : "m" (*ptr) + ); + + return res; } /** |