[PATCH 1/4] arch: local64

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* [PATCH 1/4] arch: local64_t
       [not found] <20100521134205.781916350@chello.nl>
@ 2010-05-21 13:42 ` Peter Zijlstra
  2010-05-21 14:47   ` Kyle McMartin
  2010-05-21 14:52 ` David Howells
  1 sibling, 1 reply; 3+ messages in thread
From: Peter Zijlstra @ 2010-05-21 13:42 UTC (permalink / raw)
  To: Ingo Molnar, Paul Mackerras, Arnaldo Carvalho de Melo
  Cc: Frederic Weisbecker, Steven Rostedt, David Miller, Paul Mundt,
	Will Deacon, Deng-Cheng Zhu, Peter Zijlstra, LKML, linux-arch

[-- Attachment #1: local64.patch --]
[-- Type: text/plain, Size: 10522 bytes --]

Implements local64_t.

On 64bit, local_t is of size long, and thus we make local64_t an alias.
On 32bit, we fall back to atomic64_t.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-arch@vger.kernel.org
LKML-Reference: <new-submission>
---
 arch/alpha/include/asm/local64.h      |    1 
 arch/arm/include/asm/local64.h        |    1 
 arch/avr32/include/asm/local64.h      |    1 
 arch/blackfin/include/asm/local64.h   |    1 
 arch/cris/include/asm/local64.h       |    1 
 arch/frv/include/asm/local64.h        |    1 
 arch/frv/kernel/local64.h             |    1 
 arch/h8300/include/asm/local64.h      |    1 
 arch/ia64/include/asm/local64.h       |    1 
 arch/m32r/include/asm/local64.h       |    1 
 arch/m68k/include/asm/local64.h       |    1 
 arch/microblaze/include/asm/local64.h |    1 
 arch/mips/include/asm/local64.h       |    1 
 arch/mn10300/include/asm/local64.h    |    1 
 arch/parisc/include/asm/local64.h     |    1 
 arch/powerpc/include/asm/local64.h    |    1 
 arch/s390/include/asm/local64.h       |    1 
 arch/score/include/asm/local64.h      |    1 
 arch/sh/include/asm/local64.h         |    1 
 arch/sparc/include/asm/local64.h      |    1 
 arch/x86/include/asm/local64.h        |    1 
 arch/xtensa/include/asm/local64.h     |    1 
 include/asm-generic/local64.h         |   96 ++++++++++++++++++++++++++++++++++
 23 files changed, 118 insertions(+)

Index: linux-2.6/arch/alpha/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/alpha/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/arm/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/arm/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/avr32/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/avr32/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/blackfin/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/blackfin/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/cris/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/cris/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/frv/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/frv/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/frv/kernel/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/frv/kernel/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/h8300/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/h8300/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/ia64/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/ia64/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/m32r/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/m32r/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/m68k/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/m68k/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/microblaze/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/microblaze/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/mips/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/mips/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/mn10300/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/mn10300/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/parisc/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/parisc/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/powerpc/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/powerpc/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/s390/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/s390/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/score/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/score/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/sh/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/sh/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/sparc/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/sparc/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/x86/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/x86/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/arch/xtensa/include/asm/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/xtensa/include/asm/local64.h
@@ -0,0 +1 @@
+#include <asm-generic/local64.h>
Index: linux-2.6/include/asm-generic/local64.h
===================================================================
--- /dev/null
+++ linux-2.6/include/asm-generic/local64.h
@@ -0,0 +1,96 @@
+#ifndef _ASM_GENERIC_LOCAL64_H
+#define _ASM_GENERIC_LOCAL64_H
+
+#include <linux/percpu.h>
+#include <asm/types.h>
+
+/*
+ * A signed long type for operations which are atomic for a single CPU.
+ * Usually used in combination with per-cpu variables.
+ *
+ * This is the default implementation, which uses atomic64_t.  Which is
+ * rather pointless.  The whole point behind local64_t is that some processors
+ * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
+ * running on this CPU.  local64_t allows exploitation of such capabilities.
+ */
+
+/* Implement in terms of atomics. */
+
+#if BITS_PER_LONG == 64
+
+#include <asm/local.h>
+
+typedef struct {
+	local_t a;
+} local64_t;
+
+#define LOCAL64_INIT(i)	{ LOCAL_INIT(i) }
+
+#define local64_read(l)		local_read(&(l)->a)
+#define local64_set(l,i)	local_set((&(l)->a),(i))
+#define local64_inc(l)		local_inc(&(l)->a)
+#define local64_dec(l)		local_dec(&(l)->a)
+#define local64_add(i,l)	local_add((i),(&(l)->a))
+#define local64_sub(i,l)	local_sub((i),(&(l)->a))
+
+#define local64_sub_and_test(i, l) local_sub_and_test((i), (&(l)->a))
+#define local64_dec_and_test(l) local_dec_and_test(&(l)->a)
+#define local64_inc_and_test(l) local_inc_and_test(&(l)->a)
+#define local64_add_negative(i, l) local_add_negative((i), (&(l)->a))
+#define local64_add_return(i, l) local_add_return((i), (&(l)->a))
+#define local64_sub_return(i, l) local_sub_return((i), (&(l)->a))
+#define local64_inc_return(l)	local_inc_return(&(l)->a)
+
+#define local64_cmpxchg(l, o, n) local_cmpxchg((&(l)->a), (o), (n))
+#define local64_xchg(l, n)	local_xchg((&(l)->a), (n))
+#define local64_add_unless(l, _a, u) local_add_unless((&(l)->a), (_a), (u))
+#define local64_inc_not_zero(l)	local_inc_not_zero(&(l)->a)
+
+/* Non-atomic variants, ie. preemption disabled and won't be touched
+ * in interrupt, etc.  Some archs can optimize this case well. */
+#define __local64_inc(l)	local64_set((l), local64_read(l) + 1)
+#define __local64_dec(l)	local64_set((l), local64_read(l) - 1)
+#define __local64_add(i,l)	local64_set((l), local64_read(l) + (i))
+#define __local64_sub(i,l)	local64_set((l), local64_read(l) - (i))
+
+#else /* BITS_PER_LONG != 64 */
+
+#include <asm/atomic64.h>
+
+/* Don't use typedef: don't want them to be mixed with atomic_t's. */
+typedef struct {
+	atomic64_t a;
+} local64_t;
+
+#define LOCAL64_INIT(i)	{ ATOMIC_LONG_INIT(i) }
+
+#define local64_read(l)		atomic64_read(&(l)->a)
+#define local64_set(l,i)	atomic64_set((&(l)->a),(i))
+#define local64_inc(l)		atomic64_inc(&(l)->a)
+#define local64_dec(l)		atomic64_dec(&(l)->a)
+#define local64_add(i,l)	atomic64_add((i),(&(l)->a))
+#define local64_sub(i,l)	atomic64_sub((i),(&(l)->a))
+
+#define local64_sub_and_test(i, l) atomic64_sub_and_test((i), (&(l)->a))
+#define local64_dec_and_test(l) atomic64_dec_and_test(&(l)->a)
+#define local64_inc_and_test(l) atomic64_inc_and_test(&(l)->a)
+#define local64_add_negative(i, l) atomic64_add_negative((i), (&(l)->a))
+#define local64_add_return(i, l) atomic64_add_return((i), (&(l)->a))
+#define local64_sub_return(i, l) atomic64_sub_return((i), (&(l)->a))
+#define local64_inc_return(l)	atomic64_inc_return(&(l)->a)
+
+#define local64_cmpxchg(l, o, n) atomic64_cmpxchg((&(l)->a), (o), (n))
+#define local64_xchg(l, n)	atomic64_xchg((&(l)->a), (n))
+#define local64_add_unless(l, _a, u) atomic64_add_unless((&(l)->a), (_a), (u))
+#define local64_inc_not_zero(l)	atomic64_inc_not_zero(&(l)->a)
+
+/* Non-atomic variants, ie. preemption disabled and won't be touched
+ * in interrupt, etc.  Some archs can optimize this case well. */
+#define __local64_inc(l)	local64_set((l), local64_read(l) + 1)
+#define __local64_dec(l)	local64_set((l), local64_read(l) - 1)
+#define __local64_add(i,l)	local64_set((l), local64_read(l) + (i))
+#define __local64_sub(i,l)	local64_set((l), local64_read(l) - (i))
+
+#endif /* BITS_PER_LONG != 64 */
+
+#endif /* _ASM_GENERIC_LOCAL64_H */

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH 1/4] arch: local64_t
  2010-05-21 13:42 ` [PATCH 1/4] arch: local64_t Peter Zijlstra
@ 2010-05-21 14:47   ` Kyle McMartin
  0 siblings, 0 replies; 3+ messages in thread
From: Kyle McMartin @ 2010-05-21 14:47 UTC (permalink / raw)
  To: Peter Zijlstra
  Cc: Ingo Molnar, Paul Mackerras, Arnaldo Carvalho de Melo,
	Frederic Weisbecker, Steven Rostedt, David Miller, Paul Mundt,
	Will Deacon, Deng-Cheng Zhu, LKML, linux-arch

On Fri, May 21, 2010 at 03:42:06PM +0200, Peter Zijlstra wrote:
> Implements local64_t.
> 
> On 64bit, local_t is of size long, and thus we make local64_t an alias.
> On 32bit, we fall back to atomic64_t.
> 
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: linux-arch@vger.kernel.org
> LKML-Reference: <new-submission>

Header looks good.

Acked-by: Kyle McMartin <kyle@mcmartin.ca>

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH 1/4] arch: local64_t
       [not found] <20100521134205.781916350@chello.nl>
  2010-05-21 13:42 ` [PATCH 1/4] arch: local64_t Peter Zijlstra
@ 2010-05-21 14:52 ` David Howells
  1 sibling, 0 replies; 3+ messages in thread
From: David Howells @ 2010-05-21 14:52 UTC (permalink / raw)
  To: Peter Zijlstra
  Cc: dhowells, Ingo Molnar, Paul Mackerras, Arnaldo Carvalho de Melo,
	Frederic Weisbecker, Steven Rostedt, David Miller, Paul Mundt,
	Will Deacon, Deng-Cheng Zhu, LKML, linux-arch



Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> + * This is the default implementation, which uses atomic64_t.  Which is
> + * rather pointless.  The whole point behind local64_t is that some processors
> + * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
> + * running on this CPU.  local64_t allows exploitation of such capabilities.

Interesting...  What FRV does in atomic64-ops.S should probably be rebranded
local64_t, and atomic64_t ops be based on that in non-SMP mode.

What I did on FRV was to emulate LL/ST instructions using some of the
excessive numbers of conditional bits to do so - but it only works on UP
systems.

David

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2010-05-21 14:53 UTC | newest]

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2010-05-21 13:42 ` [PATCH 1/4] arch: local64_t Peter Zijlstra
2010-05-21 14:47   ` Kyle McMartin
2010-05-21 14:52 ` David Howells

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