Reduce umtx-related work on exec and exit
- there is no need to take the process lock to iterate the thread list after single-threading is enforced - typically there are no mutexes to clean up (testable without taking the global umtx lock) - typically there is no need to adjust the priority (testable without taking thread lock) Reviewed by: kib Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D20160
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2b03b6bd45
commit
ac97da9ad8
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=347355
@ -4411,20 +4411,20 @@ umtx_exec_hook(void *arg __unused, struct proc *p,
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struct thread *td;
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KASSERT(p == curproc, ("need curproc"));
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PROC_LOCK(p);
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KASSERT((p->p_flag & P_HADTHREADS) == 0 ||
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(p->p_flag & P_STOPPED_SINGLE) != 0,
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("curproc must be single-threaded"));
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/*
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* There is no need to lock the list as only this thread can be
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* running.
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*/
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FOREACH_THREAD_IN_PROC(p, td) {
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KASSERT(td == curthread ||
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((td->td_flags & TDF_BOUNDARY) != 0 && TD_IS_SUSPENDED(td)),
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("running thread %p %p", p, td));
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PROC_UNLOCK(p);
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umtx_thread_cleanup(td);
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PROC_LOCK(p);
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td->td_rb_list = td->td_rbp_list = td->td_rb_inact = 0;
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}
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PROC_UNLOCK(p);
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}
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/*
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@ -4541,18 +4541,22 @@ umtx_thread_cleanup(struct thread *td)
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*/
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uq = td->td_umtxq;
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if (uq != NULL) {
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mtx_lock(&umtx_lock);
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uq->uq_inherited_pri = PRI_MAX;
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while ((pi = TAILQ_FIRST(&uq->uq_pi_contested)) != NULL) {
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pi->pi_owner = NULL;
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TAILQ_REMOVE(&uq->uq_pi_contested, pi, pi_link);
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if (uq->uq_inherited_pri != PRI_MAX ||
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!TAILQ_EMPTY(&uq->uq_pi_contested)) {
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mtx_lock(&umtx_lock);
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uq->uq_inherited_pri = PRI_MAX;
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while ((pi = TAILQ_FIRST(&uq->uq_pi_contested)) != NULL) {
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pi->pi_owner = NULL;
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TAILQ_REMOVE(&uq->uq_pi_contested, pi, pi_link);
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}
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mtx_unlock(&umtx_lock);
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}
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mtx_unlock(&umtx_lock);
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thread_lock(td);
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sched_lend_user_prio(td, PRI_MAX);
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thread_unlock(td);
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sched_lend_user_prio_cond(td, PRI_MAX);
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}
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if (td->td_rb_inact == 0 && td->td_rb_list == 0 && td->td_rbp_list == 0)
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return;
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/*
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* Handle terminated robust mutexes. Must be done after
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* robust pi disown, otherwise unlock could see unowned
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@ -930,6 +930,27 @@ sched_lend_user_prio(struct thread *td, u_char prio)
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td->td_flags |= TDF_NEEDRESCHED;
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}
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/*
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* Like the above but first check if there is anything to do.
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*/
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void
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sched_lend_user_prio_cond(struct thread *td, u_char prio)
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{
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if (td->td_lend_user_pri != prio)
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goto lend;
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if (td->td_user_pri != min(prio, td->td_base_user_pri))
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goto lend;
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if (td->td_priority >= td->td_user_pri)
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goto lend;
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return;
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lend:
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thread_lock(td);
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sched_lend_user_prio(td, prio);
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thread_unlock(td);
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}
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void
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sched_sleep(struct thread *td, int pri)
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{
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@ -1861,6 +1861,27 @@ sched_lend_user_prio(struct thread *td, u_char prio)
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td->td_flags |= TDF_NEEDRESCHED;
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}
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/*
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* Like the above but first check if there is anything to do.
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*/
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void
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sched_lend_user_prio_cond(struct thread *td, u_char prio)
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{
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if (td->td_lend_user_pri != prio)
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goto lend;
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if (td->td_user_pri != min(prio, td->td_base_user_pri))
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goto lend;
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if (td->td_priority >= td->td_user_pri)
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goto lend;
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return;
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lend:
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thread_lock(td);
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sched_lend_user_prio(td, prio);
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thread_unlock(td);
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}
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#ifdef SMP
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/*
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* This tdq is about to idle. Try to steal a thread from another CPU before
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@ -96,6 +96,7 @@ u_int sched_estcpu(struct thread *td);
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void sched_fork_thread(struct thread *td, struct thread *child);
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void sched_lend_prio(struct thread *td, u_char prio);
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void sched_lend_user_prio(struct thread *td, u_char pri);
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void sched_lend_user_prio_cond(struct thread *td, u_char pri);
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fixpt_t sched_pctcpu(struct thread *td);
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void sched_prio(struct thread *td, u_char prio);
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void sched_sleep(struct thread *td, int prio);
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