search for: head_spin_threshold

...t; > Right, this is really different from pvticketlocks, where the *unlock* > primitive wakes up a sleeping VCPU. It is more similar to PLE > (pause-loop exiting). Adding to the discussion, I see there are two possibilities here, considering that in undercommit cases we should not exceed HEAD_SPIN_THRESHOLD, 1. the looping vcpu in pv_head_spin_check() should do halt() considering that we have done enough spinning (more than typical lock-hold time), and hence we are in potential overcommit. 2. multiplex kick_cpu to do directed yield in qspinlock case. But this may result in some ping ponging?

...t; > Right, this is really different from pvticketlocks, where the *unlock* > primitive wakes up a sleeping VCPU. It is more similar to PLE > (pause-loop exiting). Adding to the discussion, I see there are two possibilities here, considering that in undercommit cases we should not exceed HEAD_SPIN_THRESHOLD, 1. the looping vcpu in pv_head_spin_check() should do halt() considering that we have done enough spinning (more than typical lock-hold time), and hence we are in potential overcommit. 2. multiplex kick_cpu to do directed yield in qspinlock case. But this may result in some ping ponging?

...onitoring each other to make sure they are both present. + * + * Heartbeat counters are used to track if a neighbor is active. There are + * 3 different sets of heartbeat counter monitoring going on: + * 1) The queue head will wait until the number loop iteration exceeds a + * certain threshold (HEAD_SPIN_THRESHOLD). In that case, it will send + * a kick-cpu signal to the lock holder if it has the CPU number available. + * The kick-cpu siginal will be sent only once as the real lock holder + * may not be the same as what the queue head thinks it is. + * 2) The queue head will periodically clear the a...

...ly different from pvticketlocks, where the *unlock* >> primitive wakes up a sleeping VCPU. It is more similar to PLE >> (pause-loop exiting). > > Adding to the discussion, I see there are two possibilities here, > considering that in undercommit cases we should not exceed > HEAD_SPIN_THRESHOLD, > > 1. the looping vcpu in pv_head_spin_check() should do halt() > considering that we have done enough spinning (more than typical > lock-hold time), and hence we are in potential overcommit. > > 2. multiplex kick_cpu to do directed yield in qspinlock case. > But this may res...

On 27/02/14 13:11, Paolo Bonzini wrote: > Il 27/02/2014 13:11, David Vrabel ha scritto: >>> > This patch adds para-virtualization support to the queue spinlock code >>> > by enabling the queue head to kick the lock holder CPU, if known, >>> > in when the lock isn't released for a certain amount of time. It >>> > also enables the mutual

On 27/02/14 13:11, Paolo Bonzini wrote: > Il 27/02/2014 13:11, David Vrabel ha scritto: >>> > This patch adds para-virtualization support to the queue spinlock code >>> > by enabling the queue head to kick the lock holder CPU, if known, >>> > in when the lock isn't released for a certain amount of time. It >>> > also enables the mutual

v4->v5: - Move the optimized 2-task contending code to the generic file to enable more architectures to use it without code duplication. - Address some of the style-related comments by PeterZ. - Allow the use of unfair queue spinlock in a real para-virtualized execution environment. - Add para-virtualization support to the qspinlock code by ensuring that the lock holder and queue

v4->v5: - Move the optimized 2-task contending code to the generic file to enable more architectures to use it without code duplication. - Address some of the style-related comments by PeterZ. - Allow the use of unfair queue spinlock in a real para-virtualized execution environment. - Add para-virtualization support to the qspinlock code by ensuring that the lock holder and queue

v4->v5: - Move the optimized 2-task contending code to the generic file to enable more architectures to use it without code duplication. - Address some of the style-related comments by PeterZ. - Allow the use of unfair queue spinlock in a real para-virtualized execution environment. - Add para-virtualization support to the qspinlock code by ensuring that the lock holder and queue

v4->v5: - Move the optimized 2-task contending code to the generic file to enable more architectures to use it without code duplication. - Address some of the style-related comments by PeterZ. - Allow the use of unfair queue spinlock in a real para-virtualized execution environment. - Add para-virtualization support to the qspinlock code by ensuring that the lock holder and queue