From: Alex Kogan <alex.kogan@oracle.com> To: linux@armlinux.org.uk, peterz@infradead.org, mingo@redhat.com, will.deacon@arm.com, arnd@arndb.de, longman@redhat.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, x86@kernel.org, guohanjun@huawei.com, jglauber@marvell.com Cc: steven.sistare@oracle.com, daniel.m.jordan@oracle.com, alex.kogan@oracle.com, dave.dice@oracle.com Subject: [PATCH v11 2/5] locking/qspinlock: Refactor the qspinlock slow path Date: Tue, 15 Sep 2020 14:05:32 -0400 [thread overview] Message-ID: <20200915180535.2975060-3-alex.kogan@oracle.com> (raw) In-Reply-To: <20200915180535.2975060-1-alex.kogan@oracle.com> Move some of the code manipulating the spin lock into separate functions. This would allow easier integration of alternative ways to manipulate that lock. Signed-off-by: Alex Kogan <alex.kogan@oracle.com> Reviewed-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Waiman Long <longman@redhat.com> --- kernel/locking/qspinlock.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index 435d696f9250..24b5802fc6f1 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -289,6 +289,34 @@ static __always_inline u32 __pv_wait_head_or_lock(struct qspinlock *lock, #define queued_spin_lock_slowpath native_queued_spin_lock_slowpath #endif +/* + * __try_clear_tail - try to clear tail by setting the lock value to + * _Q_LOCKED_VAL. + * @lock: Pointer to the queued spinlock structure + * @val: Current value of the lock + * @node: Pointer to the MCS node of the lock holder + */ +static __always_inline bool __try_clear_tail(struct qspinlock *lock, + u32 val, + struct mcs_spinlock *node) +{ + return atomic_try_cmpxchg_relaxed(&lock->val, &val, _Q_LOCKED_VAL); +} + +/* + * __mcs_lock_handoff - pass the MCS lock to the next waiter + * @node: Pointer to the MCS node of the lock holder + * @next: Pointer to the MCS node of the first waiter in the MCS queue + */ +static __always_inline void __mcs_lock_handoff(struct mcs_spinlock *node, + struct mcs_spinlock *next) +{ + arch_mcs_lock_handoff(&next->locked, 1); +} + +#define try_clear_tail __try_clear_tail +#define mcs_lock_handoff __mcs_lock_handoff + #endif /* _GEN_PV_LOCK_SLOWPATH */ /** @@ -533,7 +561,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) * PENDING will make the uncontended transition fail. */ if ((val & _Q_TAIL_MASK) == tail) { - if (atomic_try_cmpxchg_relaxed(&lock->val, &val, _Q_LOCKED_VAL)) + if (try_clear_tail(lock, val, node)) goto release; /* No contention */ } @@ -550,7 +578,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) if (!next) next = smp_cond_load_relaxed(&node->next, (VAL)); - arch_mcs_lock_handoff(&next->locked, 1); + mcs_lock_handoff(node, next); pv_kick_node(lock, next); release: @@ -575,6 +603,12 @@ EXPORT_SYMBOL(queued_spin_lock_slowpath); #undef pv_kick_node #undef pv_wait_head_or_lock +#undef try_clear_tail +#define try_clear_tail __try_clear_tail + +#undef mcs_lock_handoff +#define mcs_lock_handoff __mcs_lock_handoff + #undef queued_spin_lock_slowpath #define queued_spin_lock_slowpath __pv_queued_spin_lock_slowpath -- 2.21.1 (Apple Git-122.3)
WARNING: multiple messages have this Message-ID (diff)
From: Alex Kogan <alex.kogan@oracle.com> To: linux@armlinux.org.uk, peterz@infradead.org, mingo@redhat.com, will.deacon@arm.com, arnd@arndb.de, longman@redhat.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, x86@kernel.org, guohanjun@huawei.com, jglauber@marvell.com Cc: alex.kogan@oracle.com, dave.dice@oracle.com, steven.sistare@oracle.com, daniel.m.jordan@oracle.com Subject: [PATCH v11 2/5] locking/qspinlock: Refactor the qspinlock slow path Date: Tue, 15 Sep 2020 14:05:32 -0400 [thread overview] Message-ID: <20200915180535.2975060-3-alex.kogan@oracle.com> (raw) In-Reply-To: <20200915180535.2975060-1-alex.kogan@oracle.com> Move some of the code manipulating the spin lock into separate functions. This would allow easier integration of alternative ways to manipulate that lock. Signed-off-by: Alex Kogan <alex.kogan@oracle.com> Reviewed-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Waiman Long <longman@redhat.com> --- kernel/locking/qspinlock.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index 435d696f9250..24b5802fc6f1 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -289,6 +289,34 @@ static __always_inline u32 __pv_wait_head_or_lock(struct qspinlock *lock, #define queued_spin_lock_slowpath native_queued_spin_lock_slowpath #endif +/* + * __try_clear_tail - try to clear tail by setting the lock value to + * _Q_LOCKED_VAL. + * @lock: Pointer to the queued spinlock structure + * @val: Current value of the lock + * @node: Pointer to the MCS node of the lock holder + */ +static __always_inline bool __try_clear_tail(struct qspinlock *lock, + u32 val, + struct mcs_spinlock *node) +{ + return atomic_try_cmpxchg_relaxed(&lock->val, &val, _Q_LOCKED_VAL); +} + +/* + * __mcs_lock_handoff - pass the MCS lock to the next waiter + * @node: Pointer to the MCS node of the lock holder + * @next: Pointer to the MCS node of the first waiter in the MCS queue + */ +static __always_inline void __mcs_lock_handoff(struct mcs_spinlock *node, + struct mcs_spinlock *next) +{ + arch_mcs_lock_handoff(&next->locked, 1); +} + +#define try_clear_tail __try_clear_tail +#define mcs_lock_handoff __mcs_lock_handoff + #endif /* _GEN_PV_LOCK_SLOWPATH */ /** @@ -533,7 +561,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) * PENDING will make the uncontended transition fail. */ if ((val & _Q_TAIL_MASK) == tail) { - if (atomic_try_cmpxchg_relaxed(&lock->val, &val, _Q_LOCKED_VAL)) + if (try_clear_tail(lock, val, node)) goto release; /* No contention */ } @@ -550,7 +578,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) if (!next) next = smp_cond_load_relaxed(&node->next, (VAL)); - arch_mcs_lock_handoff(&next->locked, 1); + mcs_lock_handoff(node, next); pv_kick_node(lock, next); release: @@ -575,6 +603,12 @@ EXPORT_SYMBOL(queued_spin_lock_slowpath); #undef pv_kick_node #undef pv_wait_head_or_lock +#undef try_clear_tail +#define try_clear_tail __try_clear_tail + +#undef mcs_lock_handoff +#define mcs_lock_handoff __mcs_lock_handoff + #undef queued_spin_lock_slowpath #define queued_spin_lock_slowpath __pv_queued_spin_lock_slowpath -- 2.21.1 (Apple Git-122.3) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-09-15 18:37 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-09-15 18:05 [PATCH v11 0/5] Add NUMA-awareness to qspinlock Alex Kogan 2020-09-15 18:05 ` Alex Kogan 2020-09-15 18:05 ` [PATCH v11 1/5] locking/qspinlock: Rename mcs lock/unlock macros and make them more generic Alex Kogan 2020-09-15 18:05 ` Alex Kogan 2020-09-15 18:05 ` Alex Kogan [this message] 2020-09-15 18:05 ` [PATCH v11 2/5] locking/qspinlock: Refactor the qspinlock slow path Alex Kogan 2020-09-15 18:05 ` [PATCH v11 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock Alex Kogan 2020-09-15 18:05 ` Alex Kogan 2020-09-16 2:40 ` Waiman Long 2020-09-16 2:40 ` Waiman Long 2020-09-17 1:29 ` [locking/qspinlock] 5df52a74ab: reaim.jobs_per_min 45.7% improvement kernel test robot 2020-09-17 1:29 ` kernel test robot 2020-09-15 18:05 ` [PATCH v11 4/5] locking/qspinlock: Introduce starvation avoidance into CNA Alex Kogan 2020-09-15 18:05 ` Alex Kogan 2020-09-15 19:24 ` Randy Dunlap 2020-09-15 19:24 ` Randy Dunlap 2020-09-15 19:57 ` Alex Kogan 2020-09-15 19:57 ` Alex Kogan 2020-09-16 3:13 ` Waiman Long 2020-09-16 3:13 ` Waiman Long 2020-09-15 18:05 ` [PATCH v11 5/5] locking/qspinlock: Avoid moving certain threads between waiting queues in CNA Alex Kogan 2020-09-15 18:05 ` Alex Kogan
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