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Message-ID: <tip-d73a33973f16ab6703e75ea00edee857afa3406e@git.kernel.org>
Date: Fri, 8 May 2015 06:25:54 -0700
From: tip-bot for Waiman Long <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: paolo.bonzini@...il.com, boris.ostrovsky@...cle.com, bp@...en8.de,
konrad.wilk@...cle.com, riel@...hat.com, tglx@...utronix.de,
daniel@...ascale.com, peterz@...radead.org, Waiman.Long@...com,
akpm@...ux-foundation.org, paulmck@...ux.vnet.ibm.com,
oleg@...hat.com, torvalds@...ux-foundation.org,
scott.norton@...com, mingo@...nel.org,
raghavendra.kt@...ux.vnet.ibm.com, doug.hatch@...com,
hpa@...or.com, david.vrabel@...rix.com,
linux-kernel@...r.kernel.org
Subject: [tip:locking/core] locking/qspinlock, x86:
Enable x86-64 to use queued spinlocks
Commit-ID: d73a33973f16ab6703e75ea00edee857afa3406e
Gitweb: http://git.kernel.org/tip/d73a33973f16ab6703e75ea00edee857afa3406e
Author: Waiman Long <Waiman.Long@...com>
AuthorDate: Fri, 24 Apr 2015 14:56:31 -0400
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 8 May 2015 12:36:26 +0200
locking/qspinlock, x86: Enable x86-64 to use queued spinlocks
This patch makes the necessary changes at the x86 architecture
specific layer to enable the use of queued spinlocks for x86-64. As
x86-32 machines are typically not multi-socket. The benefit of queue
spinlock may not be apparent. So queued spinlocks are not enabled.
Currently, there is some incompatibilities between the para-virtualized
spinlock code (which hard-codes the use of ticket spinlock) and the
queued spinlocks. Therefore, the use of queued spinlocks is disabled
when the para-virtualized spinlock is enabled.
The arch/x86/include/asm/qspinlock.h header file includes some x86
specific optimization which will make the queueds spinlock code
perform better than the generic implementation.
Signed-off-by: Waiman Long <Waiman.Long@...com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Daniel J Blueman <daniel@...ascale.com>
Cc: David Vrabel <david.vrabel@...rix.com>
Cc: Douglas Hatch <doug.hatch@...com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Paolo Bonzini <paolo.bonzini@...il.com>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Scott J Norton <scott.norton@...com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: virtualization@...ts.linux-foundation.org
Cc: xen-devel@...ts.xenproject.org
Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/qspinlock.h | 20 ++++++++++++++++++++
arch/x86/include/asm/spinlock.h | 5 +++++
arch/x86/include/asm/spinlock_types.h | 4 ++++
4 files changed, 30 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 226d569..90b1b54 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -127,6 +127,7 @@ config X86
select MODULES_USE_ELF_RELA if X86_64
select CLONE_BACKWARDS if X86_32
select ARCH_USE_BUILTIN_BSWAP
+ select ARCH_USE_QUEUED_SPINLOCK
select ARCH_USE_QUEUE_RWLOCK
select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
select OLD_SIGACTION if X86_32
diff --git a/arch/x86/include/asm/qspinlock.h b/arch/x86/include/asm/qspinlock.h
new file mode 100644
index 0000000..e2aee82
--- /dev/null
+++ b/arch/x86/include/asm/qspinlock.h
@@ -0,0 +1,20 @@
+#ifndef _ASM_X86_QSPINLOCK_H
+#define _ASM_X86_QSPINLOCK_H
+
+#include <asm-generic/qspinlock_types.h>
+
+#define queued_spin_unlock queued_spin_unlock
+/**
+ * queued_spin_unlock - release a queued spinlock
+ * @lock : Pointer to queued spinlock structure
+ *
+ * A smp_store_release() on the least-significant byte.
+ */
+static inline void queued_spin_unlock(struct qspinlock *lock)
+{
+ smp_store_release((u8 *)lock, 0);
+}
+
+#include <asm-generic/qspinlock.h>
+
+#endif /* _ASM_X86_QSPINLOCK_H */
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 64b6117..4ec5413 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -42,6 +42,10 @@
extern struct static_key paravirt_ticketlocks_enabled;
static __always_inline bool static_key_false(struct static_key *key);
+#ifdef CONFIG_QUEUED_SPINLOCK
+#include <asm/qspinlock.h>
+#else
+
#ifdef CONFIG_PARAVIRT_SPINLOCKS
static inline void __ticket_enter_slowpath(arch_spinlock_t *lock)
@@ -196,6 +200,7 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
cpu_relax();
}
}
+#endif /* CONFIG_QUEUED_SPINLOCK */
/*
* Read-write spinlocks, allowing multiple readers
diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h
index 5f9d757..5df1f1b 100644
--- a/arch/x86/include/asm/spinlock_types.h
+++ b/arch/x86/include/asm/spinlock_types.h
@@ -23,6 +23,9 @@ typedef u32 __ticketpair_t;
#define TICKET_SHIFT (sizeof(__ticket_t) * 8)
+#ifdef CONFIG_QUEUED_SPINLOCK
+#include <asm-generic/qspinlock_types.h>
+#else
typedef struct arch_spinlock {
union {
__ticketpair_t head_tail;
@@ -33,6 +36,7 @@ typedef struct arch_spinlock {
} arch_spinlock_t;
#define __ARCH_SPIN_LOCK_UNLOCKED { { 0 } }
+#endif /* CONFIG_QUEUED_SPINLOCK */
#include <asm-generic/qrwlock_types.h>
--
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