diff options
| -rw-r--r-- | sys/kern/kern_thread.c | 48 | ||||
| -rw-r--r-- | sys/sys/proc.h | 5 |
2 files changed, 29 insertions, 24 deletions
diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c index da5eaaaf2e34..535b5289133f 100644 --- a/sys/kern/kern_thread.c +++ b/sys/kern/kern_thread.c @@ -128,9 +128,7 @@ SDT_PROBE_DEFINE(proc, , , lwp__exit); */ static uma_zone_t thread_zone; -TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); -static struct mtx zombie_lock; -MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); +static __exclusive_cache_line struct thread *thread_zombies; static void thread_zombie(struct thread *); static int thread_unsuspend_one(struct thread *td, struct proc *p, @@ -409,14 +407,20 @@ threadinit(void) /* * Place an unused thread on the zombie list. - * Use the slpq as that must be unused by now. */ void thread_zombie(struct thread *td) { - mtx_lock_spin(&zombie_lock); - TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); - mtx_unlock_spin(&zombie_lock); + struct thread *ztd; + + ztd = atomic_load_ptr(&thread_zombies); + for (;;) { + td->td_zombie = ztd; + if (atomic_fcmpset_rel_ptr((uintptr_t *)&thread_zombies, + (uintptr_t *)&ztd, (uintptr_t)td)) + break; + continue; + } } /* @@ -430,29 +434,27 @@ thread_stash(struct thread *td) } /* - * Reap zombie resources. + * Reap zombie threads. */ void thread_reap(void) { - struct thread *td_first, *td_next; + struct thread *itd, *ntd; /* - * Don't even bother to lock if none at this instant, - * we really don't care about the next instant. + * Reading upfront is pessimal if followed by concurrent atomic_swap, + * but most of the time the list is empty. */ - if (!TAILQ_EMPTY(&zombie_threads)) { - mtx_lock_spin(&zombie_lock); - td_first = TAILQ_FIRST(&zombie_threads); - if (td_first) - TAILQ_INIT(&zombie_threads); - mtx_unlock_spin(&zombie_lock); - while (td_first) { - td_next = TAILQ_NEXT(td_first, td_slpq); - thread_cow_free(td_first); - thread_free(td_first); - td_first = td_next; - } + if (thread_zombies == NULL) + return; + + itd = (struct thread *)atomic_swap_ptr((uintptr_t *)&thread_zombies, + (uintptr_t)NULL); + while (itd != NULL) { + ntd = itd->td_zombie; + thread_cow_free(itd); + thread_free(itd); + itd = ntd; } } diff --git a/sys/sys/proc.h b/sys/sys/proc.h index 474dc0f2c5b7..21b0a2f0a41c 100644 --- a/sys/sys/proc.h +++ b/sys/sys/proc.h @@ -229,7 +229,10 @@ struct thread { struct proc *td_proc; /* (*) Associated process. */ TAILQ_ENTRY(thread) td_plist; /* (*) All threads in this proc. */ TAILQ_ENTRY(thread) td_runq; /* (t) Run queue. */ - TAILQ_ENTRY(thread) td_slpq; /* (t) Sleep queue. */ + union { + TAILQ_ENTRY(thread) td_slpq; /* (t) Sleep queue. */ + struct thread *td_zombie; /* Zombie list linkage */ + }; TAILQ_ENTRY(thread) td_lockq; /* (t) Lock queue. */ LIST_ENTRY(thread) td_hash; /* (d) Hash chain. */ struct cpuset *td_cpuset; /* (t) CPU affinity mask. */ |