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| author | davidxu <davidxu@FreeBSD.org> | 2006-05-09 13:00:46 +0000 |
|---|---|---|
| committer | davidxu <davidxu@FreeBSD.org> | 2006-05-09 13:00:46 +0000 |
| commit | 122715f4f03aae8a72c0388133e44b1641f262bb (patch) | |
| tree | b4e56fb60686babbe10a0cfcdca8acebe94891b6 /sys/kern/kern_umtx.c | |
| parent | e46f79dc35ae40dddee08e3476034f36a1641791 (diff) | |
| download | FreeBSD-src-122715f4f03aae8a72c0388133e44b1641f262bb.zip FreeBSD-src-122715f4f03aae8a72c0388133e44b1641f262bb.tar.gz | |
Use wakeup_one to avoid thundering herd.
Tested by: kris
Diffstat (limited to 'sys/kern/kern_umtx.c')
| -rw-r--r-- | sys/kern/kern_umtx.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c index a4ee457..1211118 100644 --- a/sys/kern/kern_umtx.c +++ b/sys/kern/kern_umtx.c @@ -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 |
