similar to: [PATCH v2] x86, locking/spinlocks: Remove paravirt_ticketlocks_enabled

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 ---

> diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c > index e8a9ea7..25a7c43 100644 > --- a/arch/x86/xen/spinlock.c > +++ b/arch/x86/xen/spinlock.c > @@ -141,25 +141,6 @@ void __init xen_init_spinlocks(void) > pv_lock_ops.vcpu_is_preempted = PV_CALLEE_SAVE(xen_vcpu_stolen); > } > > -/* > - * While the jump_label init code needs to happend _after_ the

This patch renames the paravirt_ticketlocks_enabled static key to a more generic paravirt_spinlocks_enabled name. Signed-off-by: Waiman Long <Waiman.Long at hp.com> Signed-off-by: Peter Zijlstra <peterz at infradead.org> --- arch/x86/include/asm/spinlock.h | 4 ++-- arch/x86/kernel/kvm.c | 2 +- arch/x86/kernel/paravirt-spinlocks.c | 4 ++--

This patch renames the paravirt_ticketlocks_enabled static key to a more generic paravirt_spinlocks_enabled name. Signed-off-by: Waiman Long <Waiman.Long at hp.com> Signed-off-by: Peter Zijlstra <peterz at infradead.org> --- arch/x86/include/asm/spinlock.h | 4 ++-- arch/x86/kernel/kvm.c | 2 +- arch/x86/kernel/paravirt-spinlocks.c | 4 ++--

From: Waiman Long <Waiman.Long at hp.com> This patch renames the paravirt_ticketlocks_enabled static key to a more generic paravirt_spinlocks_enabled name. Signed-off-by: Waiman Long <Waiman.Long at hp.com> Signed-off-by: Peter Zijlstra <peterz at infradead.org> --- arch/x86/include/asm/spinlock.h | 4 ++-- arch/x86/kernel/kvm.c | 2 +-

> diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c > index e8a9ea7..a822606 100644 > --- a/arch/x86/xen/spinlock.c > +++ b/arch/x86/xen/spinlock.c > @@ -155,7 +155,6 @@ static __init int xen_init_spinlocks_jump(void) > if (!xen_domain()) > return 0; > > - static_key_slow_inc(&paravirt_ticketlocks_enabled); > return 0; > } >

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 pvops functions to reduce the size of the inlined spinlock functions. When

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 pvops functions to reduce the size of the inlined spinlock functions. When

Il 26/02/2014 16:14, Waiman Long ha scritto: > This patch adds a KVM init function to activate the unfair queue > spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config > option is selected. > > Signed-off-by: Waiman Long <Waiman.Long at hp.com> > --- > arch/x86/kernel/kvm.c | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+), 0 deletions(-)

Il 26/02/2014 16:14, Waiman Long ha scritto: > This patch adds a KVM init function to activate the unfair queue > spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config > option is selected. > > Signed-off-by: Waiman Long <Waiman.Long at hp.com> > --- > arch/x86/kernel/kvm.c | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+), 0 deletions(-)

Il 19/03/2014 21:14, Waiman Long ha scritto: > This patch adds a KVM init function to activate the unfair queue > spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config > option is selected. > > Signed-off-by: Waiman Long <Waiman.Long at hp.com> > --- > arch/x86/kernel/kvm.c | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+), 0 deletions(-)

Il 19/03/2014 21:14, Waiman Long ha scritto: > This patch adds a KVM init function to activate the unfair queue > spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config > option is selected. > > Signed-off-by: Waiman Long <Waiman.Long at hp.com> > --- > arch/x86/kernel/kvm.c | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+), 0 deletions(-)

? 2016/11/15 23:47, Peter Zijlstra ??: > On Wed, Nov 02, 2016 at 05:08:33AM -0400, Pan Xinhui wrote: >> diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h >> index 0f400c0..38c3bb7 100644 >> --- a/arch/x86/include/asm/paravirt_types.h >> +++ b/arch/x86/include/asm/paravirt_types.h >> @@ -310,6 +310,8 @@ struct pv_lock_ops {

On Wed, Feb 26, 2014 at 10:14:25AM -0500, Waiman Long wrote: > This patch adds a KVM init function to activate the unfair queue > spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config > option is selected. > > Signed-off-by: Waiman Long <Waiman.Long at hp.com> > --- > arch/x86/kernel/kvm.c | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+),

On Wed, Feb 26, 2014 at 10:14:25AM -0500, Waiman Long wrote: > This patch adds a KVM init function to activate the unfair queue > spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config > option is selected. > > Signed-off-by: Waiman Long <Waiman.Long at hp.com> > --- > arch/x86/kernel/kvm.c | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+),

On 02/26/2014 08:44 PM, Waiman Long wrote: > This patch adds a KVM init function to activate the unfair queue > spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config > option is selected. > > Signed-off-by: Waiman Long <Waiman.Long at hp.com> > --- > arch/x86/kernel/kvm.c | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+), 0 deletions(-)

On 02/26/2014 08:44 PM, Waiman Long wrote: > This patch adds a KVM init function to activate the unfair queue > spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config > option is selected. > > Signed-off-by: Waiman Long <Waiman.Long at hp.com> > --- > arch/x86/kernel/kvm.c | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+), 0 deletions(-)

Locking is always an issue in a virtualized environment because of 2 different types of problems: 1) Lock holder preemption 2) Lock waiter preemption One solution to the lock waiter preemption problem is to allow unfair lock in a virtualized environment. In this case, a new lock acquirer can come and steal the lock if the next-in-line CPU to get the lock is scheduled out. A simple unfair queue

On Wed, Nov 02, 2016 at 05:08:33AM -0400, Pan Xinhui wrote: > diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h > index 0f400c0..38c3bb7 100644 > --- a/arch/x86/include/asm/paravirt_types.h > +++ b/arch/x86/include/asm/paravirt_types.h > @@ -310,6 +310,8 @@ struct pv_lock_ops { > > void (*wait)(u8 *ptr, u8 val); > void