From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Nick Piggin" <npiggin@kernel.dk>,
"Mathieu Desnoyers" <mathieu.desnoyers@polymtl.ca>,
"Américo Wang" <xiyou.wangcong@gmail.com>,
"Eric Dumazet" <dada1@cosmosbay.com>,
"Jan Beulich" <JBeulich@novell.com>,
"Avi Kivity" <avi@redhat.com>,
Xen-devel <xen-devel@lists.xensource.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"Linux Virtualization"
<virtualization@lists.linux-foundation.org>,
"Srivatsa Vaddagiri" <vatsa@linux.vnet.ibm.com>,
"Jeremy Fitzhardinge" <jeremy.fitzhardinge@citrix.com>
Subject: [PATCH 01/14] x86/ticketlock: clean up types and accessors
Date: Tue, 16 Nov 2010 13:08:32 -0800 [thread overview]
Message-ID: <92d21a90d4e27db4b46dbacd58ef67719acd0185.1289940821.git.jeremy.fitzhardinge@citrix.com> (raw)
In-Reply-To: <cover.1289940821.git.jeremy.fitzhardinge@citrix.com>
In-Reply-To: <cover.1289940821.git.jeremy.fitzhardinge@citrix.com>
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
A few cleanups to the way spinlocks are defined and accessed:
- define __ticket_t which is the size of a spinlock ticket (ie, enough
bits to hold all the cpus)
- Define struct arch_spinlock as a union containing plain slock and
the head and tail tickets
- Use head and tail to implement some of the spinlock predicates.
- Make all ticket variables unsigned.
- Use TICKET_SHIFT to form constants
Most of this will be used in later patches.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/include/asm/spinlock.h | 24 ++++++++++--------------
arch/x86/include/asm/spinlock_types.h | 20 ++++++++++++++++++--
2 files changed, 28 insertions(+), 16 deletions(-)
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 3089f70..d6d5784 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -56,11 +56,9 @@
* much between them in performance though, especially as locks are out of line.
*/
#if (NR_CPUS < 256)
-#define TICKET_SHIFT 8
-
static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
{
- short inc = 0x0100;
+ unsigned short inc = 1 << TICKET_SHIFT;
asm volatile (
LOCK_PREFIX "xaddw %w0, %1\n"
@@ -79,7 +77,7 @@ static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)
{
- int tmp, new;
+ unsigned int tmp, new;
asm volatile("movzwl %2, %0\n\t"
"cmpb %h0,%b0\n\t"
@@ -104,12 +102,10 @@ static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)
: "memory", "cc");
}
#else
-#define TICKET_SHIFT 16
-
static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
{
- int inc = 0x00010000;
- int tmp;
+ unsigned inc = 1 << TICKET_SHIFT;
+ unsigned tmp;
asm volatile(LOCK_PREFIX "xaddl %0, %1\n"
"movzwl %w0, %2\n\t"
@@ -129,8 +125,8 @@ static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)
{
- int tmp;
- int new;
+ unsigned tmp;
+ unsigned new;
asm volatile("movl %2,%0\n\t"
"movl %0,%1\n\t"
@@ -160,16 +156,16 @@ static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)
static inline int __ticket_spin_is_locked(arch_spinlock_t *lock)
{
- int tmp = ACCESS_ONCE(lock->slock);
+ struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets);
- return !!(((tmp >> TICKET_SHIFT) ^ tmp) & ((1 << TICKET_SHIFT) - 1));
+ return !!(tmp.tail ^ tmp.head);
}
static inline int __ticket_spin_is_contended(arch_spinlock_t *lock)
{
- int tmp = ACCESS_ONCE(lock->slock);
+ struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets);
- return (((tmp >> TICKET_SHIFT) - tmp) & ((1 << TICKET_SHIFT) - 1)) > 1;
+ return ((tmp.tail - tmp.head) & TICKET_MASK) > 1;
}
#ifndef CONFIG_PARAVIRT_SPINLOCKS
diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h
index dcb48b2..e3ad1e3 100644
--- a/arch/x86/include/asm/spinlock_types.h
+++ b/arch/x86/include/asm/spinlock_types.h
@@ -5,11 +5,27 @@
# error "please don't include this file directly"
#endif
+#include <linux/types.h>
+
+#if (CONFIG_NR_CPUS < 256)
+typedef u8 __ticket_t;
+#else
+typedef u16 __ticket_t;
+#endif
+
+#define TICKET_SHIFT (sizeof(__ticket_t) * 8)
+#define TICKET_MASK ((__ticket_t)((1 << TICKET_SHIFT) - 1))
+
typedef struct arch_spinlock {
- unsigned int slock;
+ union {
+ unsigned int slock;
+ struct __raw_tickets {
+ __ticket_t head, tail;
+ } tickets;
+ };
} arch_spinlock_t;
-#define __ARCH_SPIN_LOCK_UNLOCKED { 0 }
+#define __ARCH_SPIN_LOCK_UNLOCKED { { .slock = 0 } }
typedef struct {
unsigned int lock;
--
1.7.2.3
next prev parent reply other threads:[~2010-11-16 21:11 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-16 21:08 [PATCH 00/14] PV ticket locks without expanding spinlock Jeremy Fitzhardinge
2010-11-16 21:08 ` Jeremy Fitzhardinge [this message]
2011-01-11 17:21 ` [Xen-devel] [PATCH 01/14] x86/ticketlock: clean up types and accessors Konrad Rzeszutek Wilk
2010-11-16 21:08 ` [PATCH 02/14] x86/ticketlock: convert spin loop to C Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 03/14] x86/ticketlock: Use C for __ticket_spin_unlock Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 04/14] x86/ticketlock: make large and small ticket versions of spin_lock the same Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 05/14] x86/ticketlock: make __ticket_spin_lock common Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 06/14] x86/ticketlock: make __ticket_spin_trylock common Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 07/14] x86/spinlocks: replace pv spinlocks with pv ticketlocks Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 08/14] x86/ticketlock: collapse a layer of functions Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 09/14] xen/pvticketlock: Xen implementation for PV ticket locks Jeremy Fitzhardinge
2010-11-17 8:11 ` Jan Beulich
2010-11-17 8:52 ` Jeremy Fitzhardinge
2010-11-17 9:57 ` [Xen-devel] " Jeremy Fitzhardinge
2010-11-17 10:34 ` Jan Beulich
2010-11-17 17:41 ` Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 10/14] x86/pvticketlock: use callee-save for lock_spinning Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 11/14] x86/ticketlock: don't inline _spin_unlock when using paravirt spinlocks Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 12/14] x86/ticketlocks: when paravirtualizing ticket locks, increment by 2 Jeremy Fitzhardinge
2010-11-16 21:08 ` [PATCH 13/14] x86/ticketlock: add slowpath logic Jeremy Fitzhardinge
2010-11-17 8:31 ` Jan Beulich
2010-11-17 8:52 ` Jeremy Fitzhardinge
2010-11-17 8:56 ` Jeremy Fitzhardinge
2010-11-17 9:08 ` Jeremy Fitzhardinge
2010-11-17 9:34 ` Jan Beulich
2010-11-17 8:58 ` Avi Kivity
2010-11-17 9:05 ` Jeremy Fitzhardinge
2010-11-17 9:10 ` Avi Kivity
2010-11-17 12:21 ` Peter Zijlstra
2010-11-17 15:25 ` [Xen-devel] " Jeremy Fitzhardinge
2011-01-17 15:22 ` Srivatsa Vaddagiri
2011-01-19 16:23 ` Srivatsa Vaddagiri
2011-01-24 21:56 ` Jeremy Fitzhardinge
2011-02-18 17:03 ` Srivatsa Vaddagiri
2011-01-19 18:31 ` Jeremy Fitzhardinge
2011-01-19 18:39 ` Srivatsa Vaddagiri
2011-01-19 18:55 ` Jeremy Fitzhardinge
2011-01-20 4:28 ` Srivatsa Vaddagiri
2011-01-20 9:52 ` Jan Beulich
2010-11-16 21:08 ` [PATCH 14/14] x86/ticketlocks: tidy up __ticket_unlock_kick() Jeremy Fitzhardinge
2010-11-17 8:56 ` [PATCH 00/14] PV ticket locks without expanding spinlock Avi Kivity
2011-01-19 16:44 ` Srivatsa Vaddagiri
2011-01-19 17:07 ` [PATCH 1/3] debugfs: Add support to print u32 array Srivatsa Vaddagiri
2011-01-19 17:12 ` [PATCH 2/3] kvm hypervisor : Add hypercalls to support pv-ticketlock Srivatsa Vaddagiri
2011-01-19 17:21 ` Peter Zijlstra
2011-01-19 18:29 ` Srivatsa Vaddagiri
2011-01-19 18:53 ` Jeremy Fitzhardinge
2011-01-20 11:42 ` Srivatsa Vaddagiri
2011-01-20 17:49 ` Jeremy Fitzhardinge
2011-01-20 11:59 ` Srivatsa Vaddagiri
2011-01-20 13:41 ` Peter Zijlstra
2011-01-20 14:34 ` Srivatsa Vaddagiri
2011-01-20 17:56 ` Jeremy Fitzhardinge
2011-01-21 14:02 ` Srivatsa Vaddagiri
2011-01-21 14:48 ` Rik van Riel
2011-01-22 6:14 ` Srivatsa Vaddagiri
2011-01-22 14:53 ` Rik van Riel
2011-01-24 17:49 ` Jeremy Fitzhardinge
2011-01-19 17:23 ` Srivatsa Vaddagiri
2011-01-19 17:50 ` Peter Zijlstra
2011-01-19 17:17 ` [PATCH 3/3] kvm guest : Add support for pv-ticketlocks Srivatsa Vaddagiri
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