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Use wakeup_one to avoid thundering herd.

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Tested by: kris
This commit is contained in:
David Xu 2006-05-09 13:00:46 +00:00
parent 0d0b9ff2a4
commit 005efcdb0e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=158377
1 changed files with 6 additions and 6 deletions
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12
sys/kern/kern_umtx.c
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@ -82,8 +82,8 @@ struct umtxq_chain {
struct mtx uc_lock; /* Lock for this chain. */
struct umtx_head uc_queue; /* List of sleep queues. */
#define UCF_BUSY 0x01
#define UCF_WANT 0x02
int uc_flags;
int uc_waiters;
};
#define GOLDEN_RATIO_PRIME 2654404609U
@ -135,6 +135,7 @@ umtxq_init_chains(void *arg __unused)
MTX_DEF | MTX_DUPOK);
LIST_INIT(&umtxq_chains[i].uc_queue);
umtxq_chains[i].uc_flags = 0;
umtxq_chains[i].uc_waiters = 0;
}
}
@ -166,9 +167,10 @@ umtxq_busy(struct umtx_key *key)
mtx_assert(umtxq_mtx(chain), MA_OWNED);
while (umtxq_chains[chain].uc_flags & UCF_BUSY) {
umtxq_chains[chain].uc_flags |= UCF_WANT;
umtxq_chains[chain].uc_waiters++;
msleep(&umtxq_chains[chain], umtxq_mtx(chain),
0, "umtxq_busy", 0);
umtxq_chains[chain].uc_waiters--;
}
umtxq_chains[chain].uc_flags |= UCF_BUSY;
}
@ -181,10 +183,8 @@ umtxq_unbusy(struct umtx_key *key)
mtx_assert(umtxq_mtx(chain), MA_OWNED);
KASSERT(umtxq_chains[chain].uc_flags & UCF_BUSY, ("not busy"));
umtxq_chains[chain].uc_flags &= ~UCF_BUSY;
if (umtxq_chains[chain].uc_flags & UCF_WANT) {
umtxq_chains[chain].uc_flags &= ~UCF_WANT;
wakeup(&umtxq_chains[chain]);
}
if (umtxq_chains[chain].uc_waiters)
wakeup_one(&umtxq_chains[chain]);
}
static inline void