search for: locks

...38 InnoDB: Unable to lock ./ibdata1, error: 38 InnoDB: Unable to lock ./ibdata1, error: 38 InnoDB: Unable to lock ./ibdata1, error: 38 InnoDB: Unable to lock ./ibdata1, error: 38 InnoDB: Unable to lock ./ibdata1, error: 38 InnoDB: Unable to lock ./ibdata1, error: 38 NOTE : I am using load posix-locks translator in my server vol file like this volume brick type storage/posix # POSIX FS translator option directory /mnt/mymysql/mysql #bench # Export this directory end-volume volume plocks type features/posix-locks subvolumes brick # option mandatory on e...

...peration by about 1-2% > mainly due to the use of a static key. However, uncontended lock-unlock > operation are really just a tiny percentage of a real workload. So > there should no noticeable change in application performance. No, entirely unacceptable. > +#ifdef CONFIG_VIRT_UNFAIR_LOCKS > +/** > + * queue_spin_trylock_unfair - try to acquire the queue spinlock unfairly > + * @lock : Pointer to queue spinlock structure > + * Return: 1 if lock acquired, 0 if failed > + */ > +static __always_inline int queue_spin_trylock_unfair(struct qspinlock *lock) > +{ > +...

...peration by about 1-2% > mainly due to the use of a static key. However, uncontended lock-unlock > operation are really just a tiny percentage of a real workload. So > there should no noticeable change in application performance. No, entirely unacceptable. > +#ifdef CONFIG_VIRT_UNFAIR_LOCKS > +/** > + * queue_spin_trylock_unfair - try to acquire the queue spinlock unfairly > + * @lock : Pointer to queue spinlock structure > + * Return: 1 if lock acquired, 0 if failed > + */ > +static __always_inline int queue_spin_trylock_unfair(struct qspinlock *lock) > +{ > +...

...f-by: Pan Xinhui <xinhui.pan at linux.vnet.ibm.com> > --- > arch/powerpc/include/asm/qspinlock.h | 66 +++++++++++++++++++++++++++++++ > arch/powerpc/include/asm/spinlock.h | 31 +++++++++------ > arch/powerpc/include/asm/spinlock_types.h | 4 ++ > arch/powerpc/lib/locks.c | 59 +++++++++++++++++++++++++++ > 4 files changed, 147 insertions(+), 13 deletions(-) > create mode 100644 arch/powerpc/include/asm/qspinlock.h > > diff --git a/arch/powerpc/include/asm/qspinlock.h b/arch/powerpc/include/asm/qspinlock.h > new file mode 100644 &...

...f-by: Pan Xinhui <xinhui.pan at linux.vnet.ibm.com> > --- > arch/powerpc/include/asm/qspinlock.h | 66 +++++++++++++++++++++++++++++++ > arch/powerpc/include/asm/spinlock.h | 31 +++++++++------ > arch/powerpc/include/asm/spinlock_types.h | 4 ++ > arch/powerpc/lib/locks.c | 59 +++++++++++++++++++++++++++ > 4 files changed, 147 insertions(+), 13 deletions(-) > create mode 100644 arch/powerpc/include/asm/qspinlock.h > > diff --git a/arch/powerpc/include/asm/qspinlock.h b/arch/powerpc/include/asm/qspinlock.h > new file mode 100644 &...

...0.000000] PM: Registered nosave memory: [mem 0x000a0000-0x000effff] [ 0.000000] PM: Registered nosave memory: [mem 0x000f0000-0x000fffff] [ 0.000000] e820: [mem 0x1f400000-0xfffbffff] available for PCI devices [ 0.000000] Booting paravirtualized kernel on bare hardware [ 0.000000] clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645519600211568 ns [ 0.000000] setup_percpu: NR_CPUS:512 nr_cpumask_bits:512 nr_cpu_ids:1 nr_node_ids:1 [ 0.000000] percpu: Embedded 38 pages/cpu @ffff90aadee00000 s114840 r8192 d32616 u2097152 [ 0.000000] Bui...

...s. The early part of the series is mostly unchanged: it converts the bulk of the ticket lock code into C and makes the "small" and "large" ticket code common. The only changes are the incorporation of various review comments. The latter part of the series converts from pv spinlocks to pv ticket locks (ie, using the ticket lock fastpath as-is, but adding pv ops for the ticketlock slowpaths). The significant difference here is that rather than adding a new ticket_t-sized element to arch_spinlock_t - effectively doubling the size - I steal the LSB of the tickets themselves to s...

...s. The early part of the series is mostly unchanged: it converts the bulk of the ticket lock code into C and makes the "small" and "large" ticket code common. The only changes are the incorporation of various review comments. The latter part of the series converts from pv spinlocks to pv ticket locks (ie, using the ticket lock fastpath as-is, but adding pv ops for the ticketlock slowpaths). The significant difference here is that rather than adding a new ticket_t-sized element to arch_spinlock_t - effectively doubling the size - I steal the LSB of the tickets themselves to s...

...s. The early part of the series is mostly unchanged: it converts the bulk of the ticket lock code into C and makes the "small" and "large" ticket code common. The only changes are the incorporation of various review comments. The latter part of the series converts from pv spinlocks to pv ticket locks (ie, using the ticket lock fastpath as-is, but adding pv ops for the ticketlock slowpaths). The significant difference here is that rather than adding a new ticket_t-sized element to arch_spinlock_t - effectively doubling the size - I steal the LSB of the tickets themselves to s...

To prepare for queued spinlocks. This is a simple rename except to update preprocessor guard name and a file reference. Signed-off-by: Nicholas Piggin <npiggin at gmail.com> --- arch/powerpc/include/asm/simple_spinlock.h | 292 ++++++++++++++++++ .../include/asm/simple_spinlock_types.h | 21 ++ arch/powerpc/incl...

...ome and steal the lock if the next-in-line CPU to get the lock is > scheduled out. Unfair lock in a native environment is generally not a > good idea as there is a possibility of lock starvation for a heavily > contended lock. I do not think this is a good idea -- the problems with unfair locks are worse in a virtualized guest. If a waiting VCPU deschedules and has to be kicked to grab a lock then it is very likely to lose a race with another running VCPU trying to take a lock (since it takes time for the VCPU to be rescheduled). > With the unfair locking activated on bare metal 4-so...

...ome and steal the lock if the next-in-line CPU to get the lock is > scheduled out. Unfair lock in a native environment is generally not a > good idea as there is a possibility of lock starvation for a heavily > contended lock. I do not think this is a good idea -- the problems with unfair locks are worse in a virtualized guest. If a waiting VCPU deschedules and has to be kicked to grab a lock then it is very likely to lose a race with another running VCPU trying to take a lock (since it takes time for the VCPU to be rescheduled). > With the unfair locking activated on bare metal 4-so...

...quot; 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...

...quot; 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...

...quot; 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...

...&lock->tickets.head, TICKET_LOCK_INC); /* add_smp() is a full mb() */ if (unlikely(lock->tickets.tail & TICKET_SLOWPATH_FLAG)) __ticket_unlock_slowpath(lock, prev); which is *exactly* the kind of things you cannot do with spinlocks, because after you've done the "add_smp()" and released the spinlock for the fast-path, you can't access the spinlock any more. Exactly because a fast-path lock might come in, and release the whole data structure. Linus suggested that we should not do any writes to lock after un...

...&lock->tickets.head, TICKET_LOCK_INC); /* add_smp() is a full mb() */ if (unlikely(lock->tickets.tail & TICKET_SLOWPATH_FLAG)) __ticket_unlock_slowpath(lock, prev); which is *exactly* the kind of things you cannot do with spinlocks, because after you've done the "add_smp()" and released the spinlock for the fast-path, you can't access the spinlock any more. Exactly because a fast-path lock might come in, and release the whole data structure. Linus suggested that we should not do any writes to lock after un...

...n the pending bit path qspinlock: Use a simple write to grab the lock, if applicable qspinlock: Prepare for unfair lock support qspinlock, x86: Allow unfair spinlock in a virtual guest qspinlock: Split the MCS queuing code into a separate slowerpath pvqspinlock, x86: Rename paravirt_ticketlocks_enabled pvqspinlock, x86: Add PV data structure & methods pvqspinlock: Enable coexistence with the unfair lock pvqspinlock: Add qspinlock para-virtualization support pvqspinlock, x86: Enable PV qspinlock PV for KVM pvqspinlock, x86: Enable PV qspinlock for XEN arch/x86/Kconfig...

...n the pending bit path qspinlock: Use a simple write to grab the lock, if applicable qspinlock: Prepare for unfair lock support qspinlock, x86: Allow unfair spinlock in a virtual guest qspinlock: Split the MCS queuing code into a separate slowerpath pvqspinlock, x86: Rename paravirt_ticketlocks_enabled pvqspinlock, x86: Add PV data structure & methods pvqspinlock: Enable coexistence with the unfair lock pvqspinlock: Add qspinlock para-virtualization support pvqspinlock, x86: Enable PV qspinlock PV for KVM pvqspinlock, x86: Enable PV qspinlock for XEN arch/x86/Kconfig...

...ock support qspinlock, x86: Allow unfair spinlock in a virtual guest qspinlock: Split the MCS queuing code into a separate slowerpath unfair qspinlock: Variable frequency lock stealing mechanism unfair qspinlock: Enable lock stealing in lock waiters pvqspinlock, x86: Rename paravirt_ticketlocks_enabled pvqspinlock, x86: Add PV data structure & methods pvqspinlock: Enable coexistence with the unfair lock pvqspinlock: Add qspinlock para-virtualization support pvqspinlock, x86: Enable PV qspinlock PV for KVM pvqspinlock, x86: Enable PV qspinlock for XEN arch/x86/Kconfig...