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locking/qspinlock, x86: Enable x86-64 to use queued spinlocks

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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@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel J Blueman <daniel@numascale.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Douglas Hatch <doug.hatch@hp.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <paolo.bonzini@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Waiman Long 2015-04-24 14:56:31 -04:00 committed by Ingo Molnar
parent a33fda35e3
commit d73a33973f
4 changed files with 30 additions and 0 deletions
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1
arch/x86/Kconfig
View File

@ -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

20
arch/x86/include/asm/qspinlock.h Normal file
View File

@ -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 */

5
arch/x86/include/asm/spinlock.h
View File

@ -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

4
arch/x86/include/asm/spinlock_types.h
View File

@ -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>