search for: spinlocks

There are two problems in dlm_run_purgelist 1. If a lockres is found to be in use, dlm_run_purgelist keeps trying to purge the same lockres instead of trying the next lockres. 2. When a lockres is found unused, dlm_run_purgelist releases lockres spinlock before setting DLM_LOCK_RES_DROPPING_REF and calls dlm_purge_lockres. spinlock is reacquired but in this window lockres can get reused. This

I tried building with linux-2.6.0-test7 build dies with: make[1]: Entering directory `/home/rogelio/src/klibc-0.80/klibc' gcc -Wp,-MD,./.fork.d -march=i386 -Os -fomit-frame-pointer -malign-functions=0 -malign-jumps=0 -malign-loops=0 -nostdinc -iwithprefix include -I../klibc -I../klibc/arch/i386/include -I../klibc/include/bits32 -D__KLIBC__ -DBITSIZE=32 -I../klibc/include

This is a follow-up of commit cfd8983f03c7b2 ("x86, locking/spinlocks: Remove ticket (spin)lock implementation"). The static_key structure paravirt_ticketlocks_enabled is now removed as it is no longer used. A simple build and boot test was done to verify it. Signed-off-by: Waiman Long <longman at redhat.com> --- arch/x86/include/asm/spinlock.h | 3...

This is a follow-up of commit cfd8983f03c7b2 ("x86, locking/spinlocks: Remove ticket (spin)lock implementation"). The static_key structure paravirt_ticketlocks_enabled is now removed as it is no longer used. A simple build and boot test was done to verify it. Signed-off-by: Waiman Long <longman at redhat.com> --- arch/x86/include/asm/spinlock.h | 3...

Paravirtualized spinlocks produce some overhead even if the kernel is running on bare metal. The main reason are the more complex locking and unlocking functions. Especially unlocking is no longer just one instruction but so complex that it is no longer inlined. This patch series addresses this issue by adding two more pvo...

Paravirtualized spinlocks produce some overhead even if the kernel is running on bare metal. The main reason are the more complex locking and unlocking functions. Especially unlocking is no longer just one instruction but so complex that it is no longer inlined. This patch series addresses this issue by adding two more pvo...

...pinlock.h > @@ -42,6 +42,10 @@ > extern struct static_key paravirt_ticketlocks_enabled; > static __always_inline bool static_key_false(struct static_key *key); > > +#ifdef CONFIG_QUEUE_SPINLOCK > +#include <asm/qspinlock.h> > +#else > + > #ifdef CONFIG_PARAVIRT_SPINLOCKS > > static inline void __ticket_enter_slowpath(arch_spinlock_t *lock) > @@ -180,6 +184,7 @@ static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock, > { > arch_spin_lock(lock); > } > +#endif /* CONFIG_QUEUE_SPINLOCK */ > > static inline void arch_...

...pinlock.h > @@ -42,6 +42,10 @@ > extern struct static_key paravirt_ticketlocks_enabled; > static __always_inline bool static_key_false(struct static_key *key); > > +#ifdef CONFIG_QUEUE_SPINLOCK > +#include <asm/qspinlock.h> > +#else > + > #ifdef CONFIG_PARAVIRT_SPINLOCKS > > static inline void __ticket_enter_slowpath(arch_spinlock_t *lock) > @@ -180,6 +184,7 @@ static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock, > { > arch_spin_lock(lock); > } > +#endif /* CONFIG_QUEUE_SPINLOCK */ > > static inline void arch_...

This is a follow-up of commit cfd8983f03c7b2 ("x86, locking/spinlocks: Remove ticket (spin)lock implementation"). The static_key structure paravirt_ticketlocks_enabled is now removed as it is no longer used. As a result, the init functions kvm_spinlock_init_jump() and xen_init_spinlocks_jump() are also removed. A simple build and boot test was done to verify it...

This is a follow-up of commit cfd8983f03c7b2 ("x86, locking/spinlocks: Remove ticket (spin)lock implementation"). The static_key structure paravirt_ticketlocks_enabled is now removed as it is no longer used. As a result, the init functions kvm_spinlock_init_jump() and xen_init_spinlocks_jump() are also removed. A simple build and boot test was done to verify it...

...is queue spinlock is especially suit to NUMA machines with a large number of cores as the chance of spinlock contention is much higher in those machines. The cost of contention is also higher because of slower inter-node memory traffic. The idea behind this spinlock implementation is the fact that spinlocks are acquired with preemption disabled. In other words, the process will not be migrated to another CPU while it is trying to get a spinlock. Ignoring interrupt handling, a CPU can only be contending in one spinlock at any one time. Of course, interrupt handler can try to acquire one spinlock while...

...is queue spinlock is especially suit to NUMA machines with a large number of cores as the chance of spinlock contention is much higher in those machines. The cost of contention is also higher because of slower inter-node memory traffic. The idea behind this spinlock implementation is the fact that spinlocks are acquired with preemption disabled. In other words, the process will not be migrated to another CPU while it is trying to get a spinlock. Ignoring interrupt handling, a CPU can only be contending in one spinlock at any one time. Of course, interrupt handler can try to acquire one spinlock while...

...is queue spinlock is especially suit to NUMA machines with a large number of cores as the chance of spinlock contention is much higher in those machines. The cost of contention is also higher because of slower inter-node memory traffic. The idea behind this spinlock implementation is the fact that spinlocks are acquired with preemption disabled. In other words, the process will not be migrated to another CPU while it is trying to get a spinlock. Ignoring interrupt handling, a CPU can only be contending in one spinlock at any one time. Of course, interrupt handler can try to acquire one spinlock while...

We should check dlm->dlm_state under dlm->spinlock though maybe in this case it doesn't hurt. Signed-off-by: Wengang Wang <wen.gang.wang at oracle.com> --- fs/ocfs2/dlm/dlmdomain.c | 13 ++++++------- 1 files changed, 6 insertions(+), 7 deletions(-) diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c index 6b5a492..ab82add 100644 --- a/fs/ocfs2/dlm/dlmdomain.c +++

...due to the higher slowpath overhead. This queue spinlock is especially suit to NUMA machines with a large number of cores as the chance of spinlock contention is much higher in those machines. The cost of contention is also higher because of slower inter-node memory traffic. Due to the fact that spinlocks are acquired with preemption disabled, the process will not be migrated to another CPU while it is trying to get a spinlock. Ignoring interrupt handling, a CPU can only be contending in one spinlock at any one time. Counting soft IRQ, hard IRQ and NMI, a CPU can only have a maximum of 4 concurrent...

...ket" and "large ticket" code common. Only the actual size-dependent asm instructions are specific to the ticket size. The resulting generated asm is very similar to the current hand-written code. This results in a very large reduction in lines of code. 2. Get rid of pv spinlocks, and replace them with pv ticket locks. Currently we have the notion of "pv spinlocks" where a pv-ops backend can completely replace the spinlock implementation with a new one. This has two disadvantages: - its a completely separate spinlock implementation, and - there...

...ket" and "large ticket" code common. Only the actual size-dependent asm instructions are specific to the ticket size. The resulting generated asm is very similar to the current hand-written code. This results in a very large reduction in lines of code. 2. Get rid of pv spinlocks, and replace them with pv ticket locks. Currently we have the notion of "pv spinlocks" where a pv-ops backend can completely replace the spinlock implementation with a new one. This has two disadvantages: - its a completely separate spinlock implementation, and - there...

...ket" and "large ticket" code common. Only the actual size-dependent asm instructions are specific to the ticket size. The resulting generated asm is very similar to the current hand-written code. This results in a very large reduction in lines of code. 2. Get rid of pv spinlocks, and replace them with pv ticket locks. Currently we have the notion of "pv spinlocks" where a pv-ops backend can completely replace the spinlock implementation with a new one. This has two disadvantages: - its a completely separate spinlock implementation, and - there...

...e/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -43,6 +43,10 @@ extern struct static_key paravirt_ticketlocks_enabled; static __always_inline bool static_key_false(struct static_key *key); +#ifdef CONFIG_QUEUE_SPINLOCK +#include <asm/qspinlock.h> +#else + #ifdef CONFIG_PARAVIRT_SPINLOCKS static inline void __ticket_enter_slowpath(arch_spinlock_t *lock) @@ -181,6 +185,7 @@ static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock, { arch_spin_lock(lock); } +#endif /* CONFIG_QUEUE_SPINLOCK */ static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) { di...

...e/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -43,6 +43,10 @@ extern struct static_key paravirt_ticketlocks_enabled; static __always_inline bool static_key_false(struct static_key *key); +#ifdef CONFIG_QUEUE_SPINLOCK +#include <asm/qspinlock.h> +#else + #ifdef CONFIG_PARAVIRT_SPINLOCKS static inline void __ticket_enter_slowpath(arch_spinlock_t *lock) @@ -181,6 +185,7 @@ static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock, { arch_spin_lock(lock); } +#endif /* CONFIG_QUEUE_SPINLOCK */ static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) { di...