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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 leads to BUG. This patch modifies dlm_run_purgelist to skip lockres if it's in use and purge next lockres. It also sets DLM_LOCK_RES_DROPPING_REF before...

...from fork.c:9: ../linux/include/linux/list.h:576:2: warning: #warning "don't include kernel headers in userspace" In file included from ../linux/include/linux/signal.h:5, from ../klibc/include/signal.h:12, from fork.c:9: ../linux/include/linux/spinlock.h: In function `bit_spin_lock': ../linux/include/linux/spinlock.h:413: warning: implicit declaration of function `current_thread_info' ../linux/include/linux/spinlock.h:413: invalid type argument of `->' ../linux/include/linux/spinlock.h:404: warning: unused parameter `bitnum'...

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 |...

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 |...

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 pv...

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 pv...

On Wed, Mar 19, 2014 at 04:14:00PM -0400, Waiman Long wrote: > This patch makes the necessary changes at the x86 architecture > specific layer to enable the use of queue spinlock for x86-64. As > x86-32 machines are typically not multi-socket. The benefit of queue > spinlock may not be apparent. So queue spinlock is not enabled. > > Currently, there is some incompatibilities between the para-virtualized > spinlock code (which hard-codes the use of ticket spi...

On Wed, Mar 19, 2014 at 04:14:00PM -0400, Waiman Long wrote: > This patch makes the necessary changes at the x86 architecture > specific layer to enable the use of queue spinlock for x86-64. As > x86-32 machines are typically not multi-socket. The benefit of queue > spinlock may not be apparent. So queue spinlock is not enabled. > > Currently, there is some incompatibilities between the para-virtualized > spinlock code (which hard-codes the use of ticket spi...

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 i...

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 i...

This patch introduces a new generic queue spinlock implementation that can serve as an alternative to the default ticket spinlock. Compared with the ticket spinlock, this queue spinlock should be almost as fair as the ticket spinlock. It has about the same speed in single-thread and it can be much faster in high contention situations especially whe...

This patch introduces a new queue spinlock implementation that can serve as an alternative to the default ticket spinlock. Compared with the ticket spinlock, this queue spinlock should be almost as fair as the ticket spinlock. It has about the same speed in single-thread and it can be much faster in high contention situations. Only in light...

This patch introduces a new queue spinlock implementation that can serve as an alternative to the default ticket spinlock. Compared with the ticket spinlock, this queue spinlock should be almost as fair as the ticket spinlock. It has about the same speed in single-thread and it can be much faster in high contention situations. Only in light...

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..ab82a...

From: Waiman Long <Waiman.Long at hp.com> This patch introduces a new generic queue spinlock implementation that can serve as an alternative to the default ticket spinlock. Compared with the ticket spinlock, this queue spinlock should be almost as fair as the ticket spinlock. It has about the same speed in single-thread and it can be much faster in high contention situations especially whe...

...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&...

This patch makes the necessary changes at the x86 architecture specific layer to enable the use of queue spinlock for x86-64. As x86-32 machines are typically not multi-socket. The benefit of queue spinlock may not be apparent. So queue spinlock is not enabled. Currently, there is some incompatibilities between the para-virtualized spinlock code (which hard-codes the use of ticket spinlock) and the queue spin...

This patch makes the necessary changes at the x86 architecture specific layer to enable the use of queue spinlock for x86-64. As x86-32 machines are typically not multi-socket. The benefit of queue spinlock may not be apparent. So queue spinlock is not enabled. Currently, there is some incompatibilities between the para-virtualized spinlock code (which hard-codes the use of ticket spinlock) and the queue spin...