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author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-04 11:55:10 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-04 11:55:10 -0700 |
commit | 816434ec4a674fcdb3c2221a6dffdc8f34020550 (patch) | |
tree | 6b8a319171270b20bf1b2e1c98d333f47988553a /arch/x86/include | |
parent | f357a82048ff1e5645861475b014570e11ad1911 (diff) | |
parent | 36bd621337c91a1ecda588e5bbbae8dd9698bae7 (diff) | |
download | op-kernel-dev-816434ec4a674fcdb3c2221a6dffdc8f34020550.zip op-kernel-dev-816434ec4a674fcdb3c2221a6dffdc8f34020550.tar.gz |
Merge branch 'x86-spinlocks-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 spinlock changes from Ingo Molnar:
"The biggest change here are paravirtualized ticket spinlocks (PV
spinlocks), which bring a nice speedup on various benchmarks.
The KVM host side will come to you via the KVM tree"
* 'x86-spinlocks-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/kvm/guest: Fix sparse warning: "symbol 'klock_waiting' was not declared as static"
kvm: Paravirtual ticketlocks support for linux guests running on KVM hypervisor
kvm guest: Add configuration support to enable debug information for KVM Guests
kvm uapi: Add KICK_CPU and PV_UNHALT definition to uapi
xen, pvticketlock: Allow interrupts to be enabled while blocking
x86, ticketlock: Add slowpath logic
jump_label: Split jumplabel ratelimit
x86, pvticketlock: When paravirtualizing ticket locks, increment by 2
x86, pvticketlock: Use callee-save for lock_spinning
xen, pvticketlocks: Add xen_nopvspin parameter to disable xen pv ticketlocks
xen, pvticketlock: Xen implementation for PV ticket locks
xen: Defer spinlock setup until boot CPU setup
x86, ticketlock: Collapse a layer of functions
x86, ticketlock: Don't inline _spin_unlock when using paravirt spinlocks
x86, spinlock: Replace pv spinlocks with pv ticketlocks
Diffstat (limited to 'arch/x86/include')
-rw-r--r-- | arch/x86/include/asm/kvm_para.h | 14 | ||||
-rw-r--r-- | arch/x86/include/asm/paravirt.h | 32 | ||||
-rw-r--r-- | arch/x86/include/asm/paravirt_types.h | 14 | ||||
-rw-r--r-- | arch/x86/include/asm/spinlock.h | 128 | ||||
-rw-r--r-- | arch/x86/include/asm/spinlock_types.h | 16 | ||||
-rw-r--r-- | arch/x86/include/uapi/asm/kvm_para.h | 1 |
6 files changed, 125 insertions, 80 deletions
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h index 0644129..1df1159 100644 --- a/arch/x86/include/asm/kvm_para.h +++ b/arch/x86/include/asm/kvm_para.h @@ -112,10 +112,20 @@ void kvm_async_pf_task_wait(u32 token); void kvm_async_pf_task_wake(u32 token); u32 kvm_read_and_reset_pf_reason(void); extern void kvm_disable_steal_time(void); -#else -#define kvm_guest_init() do { } while (0) + +#ifdef CONFIG_PARAVIRT_SPINLOCKS +void __init kvm_spinlock_init(void); +#else /* !CONFIG_PARAVIRT_SPINLOCKS */ +static inline void kvm_spinlock_init(void) +{ +} +#endif /* CONFIG_PARAVIRT_SPINLOCKS */ + +#else /* CONFIG_KVM_GUEST */ +#define kvm_guest_init() do {} while (0) #define kvm_async_pf_task_wait(T) do {} while(0) #define kvm_async_pf_task_wake(T) do {} while(0) + static inline u32 kvm_read_and_reset_pf_reason(void) { return 0; diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index cfdc9ee..401f350 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -712,36 +712,16 @@ static inline void __set_fixmap(unsigned /* enum fixed_addresses */ idx, #if defined(CONFIG_SMP) && defined(CONFIG_PARAVIRT_SPINLOCKS) -static inline int arch_spin_is_locked(struct arch_spinlock *lock) +static __always_inline void __ticket_lock_spinning(struct arch_spinlock *lock, + __ticket_t ticket) { - return PVOP_CALL1(int, pv_lock_ops.spin_is_locked, lock); + PVOP_VCALLEE2(pv_lock_ops.lock_spinning, lock, ticket); } -static inline int arch_spin_is_contended(struct arch_spinlock *lock) +static __always_inline void __ticket_unlock_kick(struct arch_spinlock *lock, + __ticket_t ticket) { - return PVOP_CALL1(int, pv_lock_ops.spin_is_contended, lock); -} -#define arch_spin_is_contended arch_spin_is_contended - -static __always_inline void arch_spin_lock(struct arch_spinlock *lock) -{ - PVOP_VCALL1(pv_lock_ops.spin_lock, lock); -} - -static __always_inline void arch_spin_lock_flags(struct arch_spinlock *lock, - unsigned long flags) -{ - PVOP_VCALL2(pv_lock_ops.spin_lock_flags, lock, flags); -} - -static __always_inline int arch_spin_trylock(struct arch_spinlock *lock) -{ - return PVOP_CALL1(int, pv_lock_ops.spin_trylock, lock); -} - -static __always_inline void arch_spin_unlock(struct arch_spinlock *lock) -{ - PVOP_VCALL1(pv_lock_ops.spin_unlock, lock); + PVOP_VCALL2(pv_lock_ops.unlock_kick, lock, ticket); } #endif diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 0617ff2..aab8f67 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -327,13 +327,15 @@ struct pv_mmu_ops { }; struct arch_spinlock; +#ifdef CONFIG_SMP +#include <asm/spinlock_types.h> +#else +typedef u16 __ticket_t; +#endif + struct pv_lock_ops { - int (*spin_is_locked)(struct arch_spinlock *lock); - int (*spin_is_contended)(struct arch_spinlock *lock); - void (*spin_lock)(struct arch_spinlock *lock); - void (*spin_lock_flags)(struct arch_spinlock *lock, unsigned long flags); - int (*spin_trylock)(struct arch_spinlock *lock); - void (*spin_unlock)(struct arch_spinlock *lock); + struct paravirt_callee_save lock_spinning; + void (*unlock_kick)(struct arch_spinlock *lock, __ticket_t ticket); }; /* This contains all the paravirt structures: we get a convenient diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index e0e6684..bf156de 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -1,11 +1,14 @@ #ifndef _ASM_X86_SPINLOCK_H #define _ASM_X86_SPINLOCK_H +#include <linux/jump_label.h> #include <linux/atomic.h> #include <asm/page.h> #include <asm/processor.h> #include <linux/compiler.h> #include <asm/paravirt.h> +#include <asm/bitops.h> + /* * Your basic SMP spinlocks, allowing only a single CPU anywhere * @@ -34,6 +37,31 @@ # define UNLOCK_LOCK_PREFIX #endif +/* How long a lock should spin before we consider blocking */ +#define SPIN_THRESHOLD (1 << 15) + +extern struct static_key paravirt_ticketlocks_enabled; +static __always_inline bool static_key_false(struct static_key *key); + +#ifdef CONFIG_PARAVIRT_SPINLOCKS + +static inline void __ticket_enter_slowpath(arch_spinlock_t *lock) +{ + set_bit(0, (volatile unsigned long *)&lock->tickets.tail); +} + +#else /* !CONFIG_PARAVIRT_SPINLOCKS */ +static __always_inline void __ticket_lock_spinning(arch_spinlock_t *lock, + __ticket_t ticket) +{ +} +static inline void __ticket_unlock_kick(arch_spinlock_t *lock, + __ticket_t ticket) +{ +} + +#endif /* CONFIG_PARAVIRT_SPINLOCKS */ + static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock) { return lock.tickets.head == lock.tickets.tail; @@ -52,81 +80,101 @@ static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock) * in the high part, because a wide xadd increment of the low part would carry * up and contaminate the high part. */ -static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) +static __always_inline void arch_spin_lock(arch_spinlock_t *lock) { - register struct __raw_tickets inc = { .tail = 1 }; + register struct __raw_tickets inc = { .tail = TICKET_LOCK_INC }; inc = xadd(&lock->tickets, inc); + if (likely(inc.head == inc.tail)) + goto out; + inc.tail &= ~TICKET_SLOWPATH_FLAG; for (;;) { - if (inc.head == inc.tail) - break; - cpu_relax(); - inc.head = ACCESS_ONCE(lock->tickets.head); + unsigned count = SPIN_THRESHOLD; + + do { + if (ACCESS_ONCE(lock->tickets.head) == inc.tail) + goto out; + cpu_relax(); + } while (--count); + __ticket_lock_spinning(lock, inc.tail); } - barrier(); /* make sure nothing creeps before the lock is taken */ +out: barrier(); /* make sure nothing creeps before the lock is taken */ } -static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) +static __always_inline int arch_spin_trylock(arch_spinlock_t *lock) { arch_spinlock_t old, new; old.tickets = ACCESS_ONCE(lock->tickets); - if (old.tickets.head != old.tickets.tail) + if (old.tickets.head != (old.tickets.tail & ~TICKET_SLOWPATH_FLAG)) return 0; - new.head_tail = old.head_tail + (1 << TICKET_SHIFT); + new.head_tail = old.head_tail + (TICKET_LOCK_INC << TICKET_SHIFT); /* cmpxchg is a full barrier, so nothing can move before it */ return cmpxchg(&lock->head_tail, old.head_tail, new.head_tail) == old.head_tail; } -static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) +static inline void __ticket_unlock_slowpath(arch_spinlock_t *lock, + arch_spinlock_t old) { - __add(&lock->tickets.head, 1, UNLOCK_LOCK_PREFIX); + arch_spinlock_t new; + + BUILD_BUG_ON(((__ticket_t)NR_CPUS) != NR_CPUS); + + /* Perform the unlock on the "before" copy */ + old.tickets.head += TICKET_LOCK_INC; + + /* Clear the slowpath flag */ + new.head_tail = old.head_tail & ~(TICKET_SLOWPATH_FLAG << TICKET_SHIFT); + + /* + * If the lock is uncontended, clear the flag - use cmpxchg in + * case it changes behind our back though. + */ + if (new.tickets.head != new.tickets.tail || + cmpxchg(&lock->head_tail, old.head_tail, + new.head_tail) != old.head_tail) { + /* + * Lock still has someone queued for it, so wake up an + * appropriate waiter. + */ + __ticket_unlock_kick(lock, old.tickets.head); + } } -static inline int __ticket_spin_is_locked(arch_spinlock_t *lock) +static __always_inline void arch_spin_unlock(arch_spinlock_t *lock) { - struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets); + if (TICKET_SLOWPATH_FLAG && + static_key_false(¶virt_ticketlocks_enabled)) { + arch_spinlock_t prev; - return tmp.tail != tmp.head; -} + prev = *lock; + add_smp(&lock->tickets.head, TICKET_LOCK_INC); -static inline int __ticket_spin_is_contended(arch_spinlock_t *lock) -{ - struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets); + /* add_smp() is a full mb() */ - return (__ticket_t)(tmp.tail - tmp.head) > 1; + if (unlikely(lock->tickets.tail & TICKET_SLOWPATH_FLAG)) + __ticket_unlock_slowpath(lock, prev); + } else + __add(&lock->tickets.head, TICKET_LOCK_INC, UNLOCK_LOCK_PREFIX); } -#ifndef CONFIG_PARAVIRT_SPINLOCKS - static inline int arch_spin_is_locked(arch_spinlock_t *lock) { - return __ticket_spin_is_locked(lock); -} - -static inline int arch_spin_is_contended(arch_spinlock_t *lock) -{ - return __ticket_spin_is_contended(lock); -} -#define arch_spin_is_contended arch_spin_is_contended + struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets); -static __always_inline void arch_spin_lock(arch_spinlock_t *lock) -{ - __ticket_spin_lock(lock); + return tmp.tail != tmp.head; } -static __always_inline int arch_spin_trylock(arch_spinlock_t *lock) +static inline int arch_spin_is_contended(arch_spinlock_t *lock) { - return __ticket_spin_trylock(lock); -} + struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets); -static __always_inline void arch_spin_unlock(arch_spinlock_t *lock) -{ - __ticket_spin_unlock(lock); + return (__ticket_t)(tmp.tail - tmp.head) > TICKET_LOCK_INC; } +#define arch_spin_is_contended arch_spin_is_contended static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags) @@ -134,8 +182,6 @@ static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock, arch_spin_lock(lock); } -#endif /* CONFIG_PARAVIRT_SPINLOCKS */ - static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) { while (arch_spin_is_locked(lock)) diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h index ad0ad07..4f1bea1 100644 --- a/arch/x86/include/asm/spinlock_types.h +++ b/arch/x86/include/asm/spinlock_types.h @@ -1,13 +1,17 @@ #ifndef _ASM_X86_SPINLOCK_TYPES_H #define _ASM_X86_SPINLOCK_TYPES_H -#ifndef __LINUX_SPINLOCK_TYPES_H -# error "please don't include this file directly" -#endif - #include <linux/types.h> -#if (CONFIG_NR_CPUS < 256) +#ifdef CONFIG_PARAVIRT_SPINLOCKS +#define __TICKET_LOCK_INC 2 +#define TICKET_SLOWPATH_FLAG ((__ticket_t)1) +#else +#define __TICKET_LOCK_INC 1 +#define TICKET_SLOWPATH_FLAG ((__ticket_t)0) +#endif + +#if (CONFIG_NR_CPUS < (256 / __TICKET_LOCK_INC)) typedef u8 __ticket_t; typedef u16 __ticketpair_t; #else @@ -15,6 +19,8 @@ typedef u16 __ticket_t; typedef u32 __ticketpair_t; #endif +#define TICKET_LOCK_INC ((__ticket_t)__TICKET_LOCK_INC) + #define TICKET_SHIFT (sizeof(__ticket_t) * 8) typedef struct arch_spinlock { diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h index 06fdbd9..94dc8ca 100644 --- a/arch/x86/include/uapi/asm/kvm_para.h +++ b/arch/x86/include/uapi/asm/kvm_para.h @@ -23,6 +23,7 @@ #define KVM_FEATURE_ASYNC_PF 4 #define KVM_FEATURE_STEAL_TIME 5 #define KVM_FEATURE_PV_EOI 6 +#define KVM_FEATURE_PV_UNHALT 7 /* The last 8 bits are used to indicate how to interpret the flags field * in pvclock structure. If no bits are set, all flags are ignored. |