On 04/14/2016 10:34 AM, Pan Xinhui wrote:
hello, Waiman I try your patch, thanks!also I do some improvement. below code diff has been tested, it works for me. :) diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index ce2f75e..99f31e4 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -248,7 +248,8 @@ static __always_inline void set_locked(struct qspinlock *lock) */ static __always_inline void __pv_init_node(struct mcs_spinlock *node) { } -static __always_inline void __pv_wait_node(struct mcs_spinlock *node, +static __always_inline void __pv_wait_node(struct qspinlock *lock, + struct mcs_spinlock *node, struct mcs_spinlock *prev) { } static __always_inline void __pv_kick_node(struct qspinlock *lock, struct mcs_spinlock *node) { } @@ -407,7 +408,7 @@ queue: prev = decode_tail(old); WRITE_ONCE(prev->next, node); - pv_wait_node(node, prev); + pv_wait_node(lock, node, prev); arch_mcs_spin_lock_contended(&node->locked); /* diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h index 01a6d16..75ccfd3 100644 --- a/kernel/locking/qspinlock_paravirt.h +++ b/kernel/locking/qspinlock_paravirt.h @@ -255,6 +257,19 @@ static struct pv_node *pv_unhash(struct qspinlock *lock) BUG(); } +static struct pv_node *pv_hash_lookup(struct qspinlock *lock) +{ + unsigned long offset, hash = hash_ptr(lock, pv_lock_hash_bits); + struct pv_hash_entry *he; + + for_each_hash_entry(he, offset, hash) { + if (READ_ONCE(he->lock) == lock) { + return he->node; + } + } + return NULL; +} + /* * Return true if when it is time to check the previous node which is not * in a running state. @@ -287,14 +303,17 @@ static void pv_init_node(struct mcs_spinlock *node) * pv_kick_node() is used to set _Q_SLOW_VAL and fill in hash table on its * behalf. */ -static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev) +static void pv_wait_node(struct qspinlock *lock, struct mcs_spinlock *node, + struct mcs_spinlock *prev) { struct pv_node *pn = (struct pv_node *)node; struct pv_node *pp = (struct pv_node *)prev; + struct pv_node *ph; int waitcnt = 0; int loop; bool wait_early; + pn->prev_cpu = pp->cpu; /* waitcnt processing will be compiled out if !QUEUED_LOCK_STAT */ for (;; waitcnt++) { for (wait_early = false, loop = SPIN_THRESHOLD; loop; loop--) { @@ -322,7 +341,10 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev) 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); + ph = pv_hash_lookup(lock); + if (!ph) + ph = pp; + pv_wait(&pn->state, vcpu_halted, ph->prev_cpu); } /* any comments are welcome. I put my patch here just for simplicity, or need I send it out in a new thread? thanks xinhui
I have sent out a v2 patch that incorporate your change with some minor twists.
Cheers, Longman
