locking/qspinlock, x86: Enable x86-64 to use queued spinlocks (d73a3397) · Commits · 戴 / test

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>

arch/x86/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -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

arch/x86/include/asm/qspinlock.h

0 → 100644

+20 −0

Original line number	Diff line number	Diff line
		#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 */

arch/x86/include/asm/spinlock.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -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

arch/x86/include/asm/spinlock_types.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -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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