diff options
| -rw-r--r-- | kernel/locking/qspinlock_paravirt.h | 12 | ||||
| -rw-r--r-- | kernel/locking/qspinlock_stat.h | 4 |
2 files changed, 5 insertions, 11 deletions
diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h index 429c3dc2a5f3..3acf16d79cf4 100644 --- a/kernel/locking/qspinlock_paravirt.h +++ b/kernel/locking/qspinlock_paravirt.h @@ -288,12 +288,10 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev) { struct pv_node *pn = (struct pv_node *)node; struct pv_node *pp = (struct pv_node *)prev; - int waitcnt = 0; int loop; bool wait_early; - /* waitcnt processing will be compiled out if !QUEUED_LOCK_STAT */ - for (;; waitcnt++) { + for (;;) { for (wait_early = false, loop = SPIN_THRESHOLD; loop; loop--) { if (READ_ONCE(node->locked)) return; @@ -317,7 +315,6 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev) if (!READ_ONCE(node->locked)) { qstat_inc(qstat_pv_wait_node, true); - qstat_inc(qstat_pv_wait_again, waitcnt); qstat_inc(qstat_pv_wait_early, wait_early); pv_wait(&pn->state, vcpu_halted); } @@ -458,12 +455,9 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node) pv_wait(&l->locked, _Q_SLOW_VAL); /* - * The unlocker should have freed the lock before kicking the - * CPU. So if the lock is still not free, it is a spurious - * wakeup or another vCPU has stolen the lock. The current - * vCPU should spin again. + * Because of lock stealing, the queue head vCPU may not be + * able to acquire the lock before it has to wait again. */ - qstat_inc(qstat_pv_spurious_wakeup, READ_ONCE(l->locked)); } /* diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h index b9d031516254..eb0a599fcf58 100644 --- a/kernel/locking/qspinlock_stat.h +++ b/kernel/locking/qspinlock_stat.h @@ -24,8 +24,8 @@ * pv_latency_wake - average latency (ns) from vCPU kick to wakeup * pv_lock_slowpath - # of locking operations via the slowpath * pv_lock_stealing - # of lock stealing operations - * pv_spurious_wakeup - # of spurious wakeups - * pv_wait_again - # of vCPU wait's that happened after a vCPU kick + * pv_spurious_wakeup - # of spurious wakeups in non-head vCPUs + * pv_wait_again - # of wait's after a queue head vCPU kick * pv_wait_early - # of early vCPU wait's * pv_wait_head - # of vCPU wait's at the queue head * pv_wait_node - # of vCPU wait's at a non-head queue node |