linux-kernel - [tip:perfcounters/urgent] x86: atomic64: Reduce size of functions

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Date:	Fri, 3 Jul 2009 12:43:42 GMT
From:	tip-bot for Ingo Molnar <mingo@...e.hu>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, acme@...hat.com, paulus@...ba.org,
	hpa@...or.com, mingo@...hat.com, eric.dumazet@...il.com,
	a.p.zijlstra@...llo.nl, torvalds@...ux-foundation.org,
	efault@....de, arnd@...db.de, dhowells@...hat.com,
	fweisbec@...il.com, akpm@...ux-foundation.org, tglx@...utronix.de,
	mingo@...e.hu
Subject: [tip:perfcounters/urgent] x86: atomic64: Reduce size of functions

Commit-ID:  3ac805d2afd3fa4a07cb5bcf352fd7fa83f28935
Gitweb:     http://git.kernel.org/tip/3ac805d2afd3fa4a07cb5bcf352fd7fa83f28935
Author:     Ingo Molnar <mingo@...e.hu>
AuthorDate: Fri, 3 Jul 2009 12:51:19 +0200
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 3 Jul 2009 13:26:43 +0200

x86: atomic64: Reduce size of functions

cmpxchg8b is a huge instruction in terms of register footprint,
we almost never want to inline it, not even within the same
code module.

GCC 4.3 still messes up for two functions, under-judging the
true cost of this instruction - so annotate two key functions
to reduce the bloat:

arch/x86/lib/atomic64_32.o:

   text	   data	    bss	    dec	    hex	filename
   1763	      0	      0	   1763	    6e3	atomic64_32.o.before
    435	      0	      0	    435	    1b3	atomic64_32.o.after

Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Mike Galbraith <efault@....de>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: David Howells <dhowells@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Arnd Bergmann <arnd@...db.de>
LKML-Reference: <alpine.LFD.2.01.0907021653030.3210@...alhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 arch/x86/lib/atomic64_32.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/lib/atomic64_32.c b/arch/x86/lib/atomic64_32.c
index 6195962..a910238 100644
--- a/arch/x86/lib/atomic64_32.c
+++ b/arch/x86/lib/atomic64_32.c
@@ -4,7 +4,7 @@
 #include <asm/cmpxchg.h>
 #include <asm/atomic.h>
 
-static inline u64 cmpxchg8b(u64 *ptr, u64 old, u64 new)
+static noinline u64 cmpxchg8b(u64 *ptr, u64 old, u64 new)
 {
 	u32 low = new;
 	u32 high = new >> 32;
@@ -74,7 +74,7 @@ u64 atomic64_read(atomic64_t *ptr)
  *
  * Atomically adds @delta to @ptr and returns @delta + *@ptr
  */
-u64 atomic64_add_return(u64 delta, atomic64_t *ptr)
+noinline u64 atomic64_add_return(u64 delta, atomic64_t *ptr)
 {
 	/*
 	 * Try first with a (probably incorrect) assumption about
--
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