search for: pv_qnode

...e mode 100644 index 0000000..af00eda --- /dev/null +++ b/arch/x86/include/asm/pvqspinlock.h @@ -0,0 +1,359 @@ +#ifndef _ASM_X86_PVQSPINLOCK_H +#define _ASM_X86_PVQSPINLOCK_H + +/* + * Queue Spinlock Para-Virtualization (PV) Support + * + * +------+ +------+ +------+ + * pv_qnode |Queue | prev | | prev |Queue | + * | Head |<-------| Node | .... <-| Tail | + * +------+ +------+ +------+ + * | | | + * V V V + * +------+...

...cket spinlock. Each CPU waiting for the lock will spin until it + * reaches a threshold. When that happens, it will put itself to a halt state + * so that the hypervisor can reuse the CPU cycles in some other guests as + * well as returning other hold-up CPUs faster. + * + * Auxillary fields in the pv_qnode structure are used to hold information + * relevant to the PV support so that it won't impact on the behavior and + * performance of the bare metal code. + * + * There are 2 places where races can happen: + * 1) Halting of the queue head CPU (in pv_wait_head) and the CPU + * kicking by the...

...cket spinlock. Each CPU waiting for the lock will spin until it + * reaches a threshold. When that happens, it will put itself to a halt state + * so that the hypervisor can reuse the CPU cycles in some other guests as + * well as returning other hold-up CPUs faster. + * + * Auxillary fields in the pv_qnode structure are used to hold information + * relevant to the PV support so that it won't impact on the behavior and + * performance of the bare metal code. + * + * There are 2 places where races can happen: + * 1) Halting of the queue head CPU (in pv_wait_head) and the CPU + * kicking by the...

On 10/24/2014 04:47 AM, Peter Zijlstra wrote: > On Thu, Oct 16, 2014 at 02:10:38PM -0400, Waiman Long wrote: >> +static inline void pv_init_node(struct mcs_spinlock *node) >> +{ >> + struct pv_qnode *pn = (struct pv_qnode *)node; >> + >> + BUILD_BUG_ON(sizeof(struct pv_qnode)> 5*sizeof(struct mcs_spinlock)); >> + >> + if (!pv_enabled()) >> + return; >> + >> + pn->cpustate = PV_CPU_ACTIVE; >> + pn->mayhalt = false; >> + pn->my...

On 10/24/2014 04:47 AM, Peter Zijlstra wrote: > On Thu, Oct 16, 2014 at 02:10:38PM -0400, Waiman Long wrote: >> +static inline void pv_init_node(struct mcs_spinlock *node) >> +{ >> + struct pv_qnode *pn = (struct pv_qnode *)node; >> + >> + BUILD_BUG_ON(sizeof(struct pv_qnode)> 5*sizeof(struct mcs_spinlock)); >> + >> + if (!pv_enabled()) >> + return; >> + >> + pn->cpustate = PV_CPU_ACTIVE; >> + pn->mayhalt = false; >> + pn->my...

...cket spinlock. Each CPU waiting for the lock will spin until it + * reaches a threshold. When that happens, it will put itself to a halt state + * so that the hypervisor can reuse the CPU cycles in some other guests as + * well as returning other hold-up CPUs faster. + * + * Auxillary fields in the pv_qnode structure are used to hold information + * relevant to the PV support so that it won't impact on the behavior and + * performance of the bare metal code. + * + * There are 2 places where races can happen: + * 1) Halting of the queue head CPU (in pv_wait_head) and the CPU + * kicking by the...

...cket spinlock. Each CPU waiting for the lock will spin until it + * reaches a threshold. When that happens, it will put itself to a halt state + * so that the hypervisor can reuse the CPU cycles in some other guests as + * well as returning other hold-up CPUs faster. + * + * Auxillary fields in the pv_qnode structure are used to hold information + * relevant to the PV support so that it won't impact on the behavior and + * performance of the bare metal code. + * + * There are 2 places where races can happen: + * 1) Halting of the queue head CPU (in pv_wait_head) and the CPU + * kicking by the...

...it a/arch/x86/include/asm/pvqspinlock.h b/arch/x86/include/asm/pvqspinlo index d424252..241bf30 100644 --- a/arch/x86/include/asm/pvqspinlock.h +++ b/arch/x86/include/asm/pvqspinlock.h @@ -79,9 +79,6 @@ static inline void pv_init_node(struct mcs_spinlock *node) BUILD_BUG_ON(sizeof(struct pv_qnode) > 5*sizeof(struct mcs_spinlock)); - if (!pv_enabled()) - return; - pn->cpustate = PV_CPU_ACTIVE; pn->mayhalt = false; pn->mycpu = smp_processor_id(); @@ -132,9 +129,6 @@ static inline bool pv_link_and_wait_node(u32 old, struct mcs...

...it a/arch/x86/include/asm/pvqspinlock.h b/arch/x86/include/asm/pvqspinlo index d424252..241bf30 100644 --- a/arch/x86/include/asm/pvqspinlock.h +++ b/arch/x86/include/asm/pvqspinlock.h @@ -79,9 +79,6 @@ static inline void pv_init_node(struct mcs_spinlock *node) BUILD_BUG_ON(sizeof(struct pv_qnode) > 5*sizeof(struct mcs_spinlock)); - if (!pv_enabled()) - return; - pn->cpustate = PV_CPU_ACTIVE; pn->mayhalt = false; pn->mycpu = smp_processor_id(); @@ -132,9 +129,6 @@ static inline bool pv_link_and_wait_node(u32 old, struct mcs...

On Thu, Oct 16, 2014 at 02:10:38PM -0400, Waiman Long wrote: > +static inline void pv_init_node(struct mcs_spinlock *node) > +{ > + struct pv_qnode *pn = (struct pv_qnode *)node; > + > + BUILD_BUG_ON(sizeof(struct pv_qnode) > 5*sizeof(struct mcs_spinlock)); > + > + if (!pv_enabled()) > + return; > + > + pn->cpustate = PV_CPU_ACTIVE; > + pn->mayhalt = false; > + pn->mycpu = smp_processor_id(); > +...

v11->v12: - Based on PeterZ's version of the qspinlock patch (https://lkml.org/lkml/2014/6/15/63). - Incorporated many of the review comments from Konrad Wilk and Paolo Bonzini. - The pvqspinlock code is largely from my previous version with PeterZ's way of going from queue tail to head and his idea of using callee saved calls to KVM and XEN codes. v10->v11: - Use a

v11->v12: - Based on PeterZ's version of the qspinlock patch (https://lkml.org/lkml/2014/6/15/63). - Incorporated many of the review comments from Konrad Wilk and Paolo Bonzini. - The pvqspinlock code is largely from my previous version with PeterZ's way of going from queue tail to head and his idea of using callee saved calls to KVM and XEN codes. v10->v11: - Use a

v13->v14: - Patches 1 & 2: Add queue_spin_unlock_wait() to accommodate commit 78bff1c86 from Oleg Nesterov. - Fix the system hang problem when using PV qspinlock in an over-committed guest due to a racing condition in the pv_set_head_in_tail() function. - Increase the MAYHALT_THRESHOLD from 10 to 1024. - Change kick_cpu into a regular function pointer instead of a

v13->v14: - Patches 1 & 2: Add queue_spin_unlock_wait() to accommodate commit 78bff1c86 from Oleg Nesterov. - Fix the system hang problem when using PV qspinlock in an over-committed guest due to a racing condition in the pv_set_head_in_tail() function. - Increase the MAYHALT_THRESHOLD from 10 to 1024. - Change kick_cpu into a regular function pointer instead of a

v12->v13: - Change patch 9 to generate separate versions of the queue_spin_lock_slowpath functions for bare metal and PV guest. This reduces the performance impact of the PV code on bare metal systems. v11->v12: - Based on PeterZ's version of the qspinlock patch (https://lkml.org/lkml/2014/6/15/63). - Incorporated many of the review comments from Konrad Wilk and Paolo

v12->v13: - Change patch 9 to generate separate versions of the queue_spin_lock_slowpath functions for bare metal and PV guest. This reduces the performance impact of the PV code on bare metal systems. v11->v12: - Based on PeterZ's version of the qspinlock patch (https://lkml.org/lkml/2014/6/15/63). - Incorporated many of the review comments from Konrad Wilk and Paolo

v10->v11: - Use a simple test-and-set unfair lock to simplify the code, but performance may suffer a bit for large guest with many CPUs. - Take out Raghavendra KT's test results as the unfair lock changes may render some of his results invalid. - Add PV support without increasing the size of the core queue node structure. - Other minor changes to address some of the

v10->v11: - Use a simple test-and-set unfair lock to simplify the code, but performance may suffer a bit for large guest with many CPUs. - Take out Raghavendra KT's test results as the unfair lock changes may render some of his results invalid. - Add PV support without increasing the size of the core queue node structure. - Other minor changes to address some of the