From 0b17c9670590148656645be57f62f279f0d3ad52 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Fri, 9 Jun 2017 17:26:43 -0700 Subject: [PATCH] MIPS: Use queued spinlocks (qspinlock) This patch switches MIPS to make use of generically implemented queued spinlocks, rather than the ticket spinlocks used previously. This allows us to drop a whole load of inline assembly, share more generic code, and is also a performance win. Results from running the AIM7 short workload on a MIPS Creator Ci40 (ie. 2 core 2 thread interAptiv CPU clocked at 546MHz) with v4.12-rc4 pistachio_defconfig, with ftrace disabled due to a current bug, and both with & without use of queued rwlocks & spinlocks: Forks | v4.12-rc4 | +qlocks | Change -------|-----------|----------|-------- 10 | 52630.32 | 53316.31 | +1.01% 20 | 51777.80 | 52623.15 | +1.02% 30 | 51645.92 | 52517.26 | +1.02% 40 | 51634.88 | 52419.89 | +1.02% 50 | 51506.75 | 52307.81 | +1.02% 60 | 51500.74 | 52322.72 | +1.02% 70 | 51434.81 | 52288.60 | +1.02% 80 | 51423.22 | 52434.85 | +1.02% 90 | 51428.65 | 52410.10 | +1.02% The kernels used for these tests also had my "MIPS: Hardcode cpu_has_* where known at compile time due to ISA" patch applied, which allows the kernel_uses_llsc checks in cmpxchg() & xchg() to be optimised away at compile time. Signed-off-by: Paul Burton Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/16358/ Signed-off-by: Ralf Baechle --- arch/mips/Kconfig | 1 + arch/mips/include/asm/Kbuild | 1 + arch/mips/include/asm/spinlock.h | 210 +------------------------ arch/mips/include/asm/spinlock_types.h | 24 +-- 4 files changed, 4 insertions(+), 232 deletions(-) diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 7c2a64b321790..ef1cb20cfbb37 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -12,6 +12,7 @@ config MIPS select ARCH_USE_BUILTIN_BSWAP select ARCH_USE_CMPXCHG_LOCKREF if 64BIT select ARCH_USE_QUEUED_RWLOCKS + select ARCH_USE_QUEUED_SPINLOCKS select ARCH_WANT_IPC_PARSE_VERSION select BUILDTIME_EXTABLE_SORT select CLONE_BACKWARDS diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild index ae6cb47e9d222..7c8aab23bce8d 100644 --- a/arch/mips/include/asm/Kbuild +++ b/arch/mips/include/asm/Kbuild @@ -13,6 +13,7 @@ generic-y += parport.h generic-y += percpu.h generic-y += preempt.h generic-y += qrwlock.h +generic-y += qspinlock.h generic-y += sections.h generic-y += segment.h generic-y += serial.h diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h index 3e7afff196cd5..a7d21da16b6a0 100644 --- a/arch/mips/include/asm/spinlock.h +++ b/arch/mips/include/asm/spinlock.h @@ -9,217 +9,9 @@ #ifndef _ASM_SPINLOCK_H #define _ASM_SPINLOCK_H -#include - -#include #include #include -#include -#include - -/* - * Your basic SMP spinlocks, allowing only a single CPU anywhere - * - * Simple spin lock operations. There are two variants, one clears IRQ's - * on the local processor, one does not. - * - * These are fair FIFO ticket locks - * - * (the type definitions are in asm/spinlock_types.h) - */ - - -/* - * Ticket locks are conceptually two parts, one indicating the current head of - * the queue, and the other indicating the current tail. The lock is acquired - * by atomically noting the tail and incrementing it by one (thus adding - * ourself to the queue and noting our position), then waiting until the head - * becomes equal to the the initial value of the tail. - */ - -static inline int arch_spin_is_locked(arch_spinlock_t *lock) -{ - u32 counters = ACCESS_ONCE(lock->lock); - - return ((counters >> 16) ^ counters) & 0xffff; -} - -static inline int arch_spin_value_unlocked(arch_spinlock_t lock) -{ - return lock.h.serving_now == lock.h.ticket; -} - -#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) - -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - u16 owner = READ_ONCE(lock->h.serving_now); - smp_rmb(); - for (;;) { - arch_spinlock_t tmp = READ_ONCE(*lock); - - if (tmp.h.serving_now == tmp.h.ticket || - tmp.h.serving_now != owner) - break; - - cpu_relax(); - } - smp_acquire__after_ctrl_dep(); -} - -static inline int arch_spin_is_contended(arch_spinlock_t *lock) -{ - u32 counters = ACCESS_ONCE(lock->lock); - - return (((counters >> 16) - counters) & 0xffff) > 1; -} -#define arch_spin_is_contended arch_spin_is_contended - -static inline void arch_spin_lock(arch_spinlock_t *lock) -{ - int my_ticket; - int tmp; - int inc = 0x10000; - - if (R10000_LLSC_WAR) { - __asm__ __volatile__ ( - " .set push # arch_spin_lock \n" - " .set noreorder \n" - " \n" - "1: ll %[ticket], %[ticket_ptr] \n" - " addu %[my_ticket], %[ticket], %[inc] \n" - " sc %[my_ticket], %[ticket_ptr] \n" - " beqzl %[my_ticket], 1b \n" - " nop \n" - " srl %[my_ticket], %[ticket], 16 \n" - " andi %[ticket], %[ticket], 0xffff \n" - " bne %[ticket], %[my_ticket], 4f \n" - " subu %[ticket], %[my_ticket], %[ticket] \n" - "2: \n" - " .subsection 2 \n" - "4: andi %[ticket], %[ticket], 0xffff \n" - " sll %[ticket], 5 \n" - " \n" - "6: bnez %[ticket], 6b \n" - " subu %[ticket], 1 \n" - " \n" - " lhu %[ticket], %[serving_now_ptr] \n" - " beq %[ticket], %[my_ticket], 2b \n" - " subu %[ticket], %[my_ticket], %[ticket] \n" - " b 4b \n" - " subu %[ticket], %[ticket], 1 \n" - " .previous \n" - " .set pop \n" - : [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock), - [serving_now_ptr] "+m" (lock->h.serving_now), - [ticket] "=&r" (tmp), - [my_ticket] "=&r" (my_ticket) - : [inc] "r" (inc)); - } else { - __asm__ __volatile__ ( - " .set push # arch_spin_lock \n" - " .set noreorder \n" - " \n" - "1: ll %[ticket], %[ticket_ptr] \n" - " addu %[my_ticket], %[ticket], %[inc] \n" - " sc %[my_ticket], %[ticket_ptr] \n" - " beqz %[my_ticket], 1b \n" - " srl %[my_ticket], %[ticket], 16 \n" - " andi %[ticket], %[ticket], 0xffff \n" - " bne %[ticket], %[my_ticket], 4f \n" - " subu %[ticket], %[my_ticket], %[ticket] \n" - "2: .insn \n" - " .subsection 2 \n" - "4: andi %[ticket], %[ticket], 0xffff \n" - " sll %[ticket], 5 \n" - " \n" - "6: bnez %[ticket], 6b \n" - " subu %[ticket], 1 \n" - " \n" - " lhu %[ticket], %[serving_now_ptr] \n" - " beq %[ticket], %[my_ticket], 2b \n" - " subu %[ticket], %[my_ticket], %[ticket] \n" - " b 4b \n" - " subu %[ticket], %[ticket], 1 \n" - " .previous \n" - " .set pop \n" - : [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock), - [serving_now_ptr] "+m" (lock->h.serving_now), - [ticket] "=&r" (tmp), - [my_ticket] "=&r" (my_ticket) - : [inc] "r" (inc)); - } - - smp_llsc_mb(); -} - -static inline void arch_spin_unlock(arch_spinlock_t *lock) -{ - unsigned int serving_now = lock->h.serving_now + 1; - wmb(); - lock->h.serving_now = (u16)serving_now; - nudge_writes(); -} - -static inline unsigned int arch_spin_trylock(arch_spinlock_t *lock) -{ - int tmp, tmp2, tmp3; - int inc = 0x10000; - - if (R10000_LLSC_WAR) { - __asm__ __volatile__ ( - " .set push # arch_spin_trylock \n" - " .set noreorder \n" - " \n" - "1: ll %[ticket], %[ticket_ptr] \n" - " srl %[my_ticket], %[ticket], 16 \n" - " andi %[now_serving], %[ticket], 0xffff \n" - " bne %[my_ticket], %[now_serving], 3f \n" - " addu %[ticket], %[ticket], %[inc] \n" - " sc %[ticket], %[ticket_ptr] \n" - " beqzl %[ticket], 1b \n" - " li %[ticket], 1 \n" - "2: \n" - " .subsection 2 \n" - "3: b 2b \n" - " li %[ticket], 0 \n" - " .previous \n" - " .set pop \n" - : [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock), - [ticket] "=&r" (tmp), - [my_ticket] "=&r" (tmp2), - [now_serving] "=&r" (tmp3) - : [inc] "r" (inc)); - } else { - __asm__ __volatile__ ( - " .set push # arch_spin_trylock \n" - " .set noreorder \n" - " \n" - "1: ll %[ticket], %[ticket_ptr] \n" - " srl %[my_ticket], %[ticket], 16 \n" - " andi %[now_serving], %[ticket], 0xffff \n" - " bne %[my_ticket], %[now_serving], 3f \n" - " addu %[ticket], %[ticket], %[inc] \n" - " sc %[ticket], %[ticket_ptr] \n" - " beqz %[ticket], 1b \n" - " li %[ticket], 1 \n" - "2: .insn \n" - " .subsection 2 \n" - "3: b 2b \n" - " li %[ticket], 0 \n" - " .previous \n" - " .set pop \n" - : [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock), - [ticket] "=&r" (tmp), - [my_ticket] "=&r" (tmp2), - [now_serving] "=&r" (tmp3) - : [inc] "r" (inc)); - } - - smp_llsc_mb(); - - return tmp; -} +#include #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) diff --git a/arch/mips/include/asm/spinlock_types.h b/arch/mips/include/asm/spinlock_types.h index 3d38bfad9b490..177e722eb96cc 100644 --- a/arch/mips/include/asm/spinlock_types.h +++ b/arch/mips/include/asm/spinlock_types.h @@ -1,29 +1,7 @@ #ifndef _ASM_SPINLOCK_TYPES_H #define _ASM_SPINLOCK_TYPES_H -#include - -#include - -typedef union { - /* - * bits 0..15 : serving_now - * bits 16..31 : ticket - */ - u32 lock; - struct { -#ifdef __BIG_ENDIAN - u16 ticket; - u16 serving_now; -#else - u16 serving_now; - u16 ticket; -#endif - } h; -} arch_spinlock_t; - -#define __ARCH_SPIN_LOCK_UNLOCKED { .lock = 0 } - +#include #include #endif -- 2.39.5