search for: pv_cpu_halt

...othing, just go to sleep. Could you get (or do you have) numbers for (2)? More important, I think a barrier is missing: Lock holder --------------------------------------- // queue_spin_unlock barrier(); ACCESS_ONCE(qlock->lock) = 0; barrier(); // pv_kick_node: if (pv->cpustate != PV_CPU_HALTED) return; ACCESS_ONCE(pv->cpustate) = PV_CPU_KICKED; __queue_kick_cpu(pv->mycpu, PV_KICK_QUEUE_HEAD); Waiter ------------------------------------------- // pv_head_spin_check ACCESS_ONCE(pv->cpustate) = PV_CPU_HALTED; lockval = cmpxchg(&qlock->lock, _QSPINLOCK_L...

On 12/03/14 18:54, Waiman Long wrote: > This patch adds para-virtualization support to the queue spinlock in > the same way as was done in the PV ticket lock code. In essence, the > lock waiters will spin for a specified number of times (QSPIN_THRESHOLD > = 2^14) and then halted itself. The queue head waiter will spins > 2*QSPIN_THRESHOLD times before halting itself. When it has

On 12/03/14 18:54, Waiman Long wrote: > This patch adds para-virtualization support to the queue spinlock in > the same way as was done in the PV ticket lock code. In essence, the > lock waiters will spin for a specified number of times (QSPIN_THRESHOLD > = 2^14) and then halted itself. The queue head waiter will spins > 2*QSPIN_THRESHOLD times before halting itself. When it has

...== _QSPINLOCK_LOCKED)) return; else queue_spin_unlock_slowpath(lock); } else { __queue_spin_unlock(lock); } > // pv_kick_node: > if (pv->cpustate != PV_CPU_HALTED) > return; > ACCESS_ONCE(pv->cpustate) = PV_CPU_KICKED; > __queue_kick_cpu(pv->mycpu, PV_KICK_QUEUE_HEAD); > > Waiter ------------------------------------------- > > // pv_head_spin_check > ACCESS_ONCE(pv->cpustate) = PV_CPU...

...== _QSPINLOCK_LOCKED)) return; else queue_spin_unlock_slowpath(lock); } else { __queue_spin_unlock(lock); } > // pv_kick_node: > if (pv->cpustate != PV_CPU_HALTED) > return; > ACCESS_ONCE(pv->cpustate) = PV_CPU_KICKED; > __queue_kick_cpu(pv->mycpu, PV_KICK_QUEUE_HEAD); > > Waiter ------------------------------------------- > > // pv_head_spin_check > ACCESS_ONCE(pv->cpustate) = PV_CPU...

.... + */ + +/* + * Spin threshold for queue spinlock + */ +#define QSPIN_THRESHOLD (1U<<14) +#define MAYHALT_THRESHOLD (QSPIN_THRESHOLD - 0x10) + +/* + * CPU state flags + */ +#define PV_CPU_ACTIVE 1 /* This CPU is active */ +#define PV_CPU_KICKED 2 /* This CPU is being kicked */ +#define PV_CPU_HALTED -1 /* This CPU is halted */ + +/* + * Additional fields to be added to the queue node structure + * + * The size of the mcs_spinlock structure is 16 bytes for x64 and 12 bytes + * for i386. Four of those structures are defined per CPU. To add more fields + * without increasing the size of the m...

...being + * addressed. + */ + +/* + * Spin thresholds for queue spinlock + */ +#define QSPIN_THRESHOLD SPIN_THRESHOLD +#define MAYHALT_THRESHOLD 0x10 + +/* + * CPU state flags + */ +#define PV_CPU_ACTIVE 1 /* This CPU is active */ +#define PV_CPU_KICKED 2 /* This CPU is being kicked */ +#define PV_CPU_HALTED -1 /* This CPU is halted */ + +/* + * Special head node pointer value + */ +#define PV_INVALID_HEAD NULL + +/* + * Additional fields to be added to the queue node structure + * + * The size of the mcs_spinlock structure is 16 bytes for x64 and 12 bytes + * for i386. Four of those structures are...

...being + * addressed. + */ + +/* + * Spin thresholds for queue spinlock + */ +#define QSPIN_THRESHOLD SPIN_THRESHOLD +#define MAYHALT_THRESHOLD 0x10 + +/* + * CPU state flags + */ +#define PV_CPU_ACTIVE 1 /* This CPU is active */ +#define PV_CPU_KICKED 2 /* This CPU is being kicked */ +#define PV_CPU_HALTED -1 /* This CPU is halted */ + +/* + * Special head node pointer value + */ +#define PV_INVALID_HEAD NULL + +/* + * Additional fields to be added to the queue node structure + * + * The size of the mcs_spinlock structure is 16 bytes for x64 and 12 bytes + * for i386. Four of those structures are...

...being + * addressed. + */ + +/* + * Spin thresholds for queue spinlock + */ +#define QSPIN_THRESHOLD SPIN_THRESHOLD +#define MAYHALT_THRESHOLD 0x10 + +/* + * CPU state flags + */ +#define PV_CPU_ACTIVE 1 /* This CPU is active */ +#define PV_CPU_KICKED 2 /* This CPU is being kicked */ +#define PV_CPU_HALTED -1 /* This CPU is halted */ + +/* + * Special head node pointer value + */ +#define PV_INVALID_HEAD NULL + +/* + * Additional fields to be added to the queue node structure + * + * The size of the mcs_spinlock structure is 16 bytes for x64 and 12 bytes + * for i386. Four of those structures are...

...being + * addressed. + */ + +/* + * Spin thresholds for queue spinlock + */ +#define QSPIN_THRESHOLD SPIN_THRESHOLD +#define MAYHALT_THRESHOLD 0x10 + +/* + * CPU state flags + */ +#define PV_CPU_ACTIVE 1 /* This CPU is active */ +#define PV_CPU_KICKED 2 /* This CPU is being kicked */ +#define PV_CPU_HALTED -1 /* This CPU is halted */ + +/* + * Special head node pointer value + */ +#define PV_INVALID_HEAD NULL + +/* + * Additional fields to be added to the queue node structure + * + * The size of the mcs_spinlock structure is 16 bytes for x64 and 12 bytes + * for i386. Four of those structures are...

...ros + */ +#define PV_SET_VAR(type, var, val) type var = val +#define PV_VAR(var) var + +/* + * CPU state flags + */ +#define PV_CPU_ACTIVE 1 /* This CPU is active */ +#define PV_CPU_KICKING 2 /* This CPU is kicking other CPU */ +#define PV_CPU_KICKED 3 /* This CPU is being kicked */ +#define PV_CPU_HALTED -1 /* This CPU is halted */ + +/* + * Additional fields to be added to the qnode structure + */ +#if CONFIG_NR_CPUS >= (1 << 16) +#define _cpuid_t u32 +#else +#define _cpuid_t u16 +#endif + +struct qnode; + +struct pv_qvars { + s16 cpustate; /* CPU status flag */ + _cpuid_t...

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

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

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

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

v8->v9: - Integrate PeterZ's version of the queue spinlock patch with some modification: http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org - Break the more complex patches into smaller ones to ease review effort. - Fix a racing condition in the PV qspinlock code. v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving