diff options
author | Seigo Tanimura <tanimura@FreeBSD.org> | 2002-07-30 06:54:05 +0000 |
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committer | Seigo Tanimura <tanimura@FreeBSD.org> | 2002-07-30 06:54:05 +0000 |
commit | 9eb881f804d7dc209adca1d5181afa2a97402fb8 (patch) | |
tree | 0c83be03d1e2e71dfad7f8b959ebd86dd9b9546f /sys/vm/vm_glue.c | |
parent | bfd2867046a1c9cbe2de44480ff995e7d43060bb (diff) | |
download | src-9eb881f804d7dc209adca1d5181afa2a97402fb8.tar.gz src-9eb881f804d7dc209adca1d5181afa2a97402fb8.zip |
- Optimize wakeup() and its friends; if a thread waken up is being
swapped in, we do not have to ask for the scheduler thread to do
that.
- Assert that a process is not swapped out in runq functions and
swapout().
- Introduce thread_safetoswapout() for readability.
- In swapout_procs(), perform a test that may block (check of a
thread working on its vm map) first. This lets us call swapout()
with the sched_lock held, providing a better atomicity.
Notes
Notes:
svn path=/head/; revision=100913
Diffstat (limited to 'sys/vm/vm_glue.c')
-rw-r--r-- | sys/vm/vm_glue.c | 129 |
1 files changed, 65 insertions, 64 deletions
diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c index 8572a23f6846..ff8b3df50853 100644 --- a/sys/vm/vm_glue.c +++ b/sys/vm/vm_glue.c @@ -511,12 +511,12 @@ faultin(p) PROC_LOCK(p); mtx_lock_spin(&sched_lock); + p->p_sflag &= ~PS_SWAPPINGIN; + p->p_sflag |= PS_INMEM; FOREACH_THREAD_IN_PROC (p, td) if (td->td_state == TDS_SWAPPED) setrunqueue(td); - p->p_sflag &= ~PS_SWAPPINGIN; - p->p_sflag |= PS_INMEM; wakeup(&p->p_sflag); /* undo the effect of setting SLOCK above */ @@ -671,32 +671,42 @@ retry: struct vmspace *vm; int minslptime = 100000; + /* + * Do not swapout a process that + * is waiting for VM data + * structures there is a possible + * deadlock. Test this first as + * this may block. + * + * Lock the map until swapout + * finishes, or a thread of this + * process may attempt to alter + * the map. + */ + vm = p->p_vmspace; + ++vm->vm_refcnt; + if (!vm_map_trylock(&vm->vm_map)) + goto nextproc1; + PROC_LOCK(p); if (p->p_lock != 0 || (p->p_flag & (P_STOPPED_SNGL|P_TRACED|P_SYSTEM|P_WEXIT)) != 0) { - PROC_UNLOCK(p); - continue; + goto nextproc2; } /* * only aiod changes vmspace, however it will be * skipped because of the if statement above checking * for P_SYSTEM */ - vm = p->p_vmspace; mtx_lock_spin(&sched_lock); - if ((p->p_sflag & (PS_INMEM|PS_SWAPPING|PS_SWAPPINGIN)) != PS_INMEM) { - mtx_unlock_spin(&sched_lock); - PROC_UNLOCK(p); - continue; - } + if ((p->p_sflag & (PS_INMEM|PS_SWAPPING|PS_SWAPPINGIN)) != PS_INMEM) + goto nextproc; switch (p->p_state) { default: /* Don't swap out processes in any sort * of 'special' state. */ - mtx_unlock_spin(&sched_lock); - PROC_UNLOCK(p); - continue; + goto nextproc; case PRS_NORMAL: /* @@ -704,39 +714,29 @@ retry: * Check all the thread groups.. */ FOREACH_KSEGRP_IN_PROC(p, kg) { - if (PRI_IS_REALTIME(kg->kg_pri_class)) { - mtx_unlock_spin(&sched_lock); - PROC_UNLOCK(p); + if (PRI_IS_REALTIME(kg->kg_pri_class)) goto nextproc; - } /* - * Do not swapout a process waiting - * on a critical event of some kind. - * Also guarantee swap_idle_threshold1 + * Guarantee swap_idle_threshold1 * time in memory. */ - if (kg->kg_slptime < swap_idle_threshold1) { - mtx_unlock_spin(&sched_lock); - PROC_UNLOCK(p); + if (kg->kg_slptime < swap_idle_threshold1) goto nextproc; - } + /* - * Do not swapout a process if there is - * a thread whose pageable memory may - * be accessed. + * Do not swapout a process if it is + * waiting on a critical event of some + * kind or there is a thread whose + * pageable memory may be accessed. * * This could be refined to support * swapping out a thread. */ - FOREACH_THREAD_IN_PROC(p, td) { + FOREACH_THREAD_IN_GROUP(kg, td) { if ((td->td_priority) < PSOCK || - !(td->td_state == TDS_SLP || - td->td_state == TDS_RUNQ)) { - mtx_unlock_spin(&sched_lock); - PROC_UNLOCK(p); + !thread_safetoswapout(td)) goto nextproc; - } } /* * If the system is under memory stress, @@ -746,29 +746,13 @@ retry: */ if (((action & VM_SWAP_NORMAL) == 0) && (((action & VM_SWAP_IDLE) == 0) || - (kg->kg_slptime < swap_idle_threshold2))) { - mtx_unlock_spin(&sched_lock); - PROC_UNLOCK(p); + (kg->kg_slptime < swap_idle_threshold2))) goto nextproc; - } + if (minslptime > kg->kg_slptime) minslptime = kg->kg_slptime; } - mtx_unlock_spin(&sched_lock); - ++vm->vm_refcnt; - /* - * do not swapout a process that - * is waiting for VM - * data structures there is a - * possible deadlock. - */ - if (!vm_map_trylock(&vm->vm_map)) { - vmspace_free(vm); - PROC_UNLOCK(p); - goto nextproc; - } - vm_map_unlock(&vm->vm_map); /* * If the process has been asleep for awhile and had * most of its pages taken away already, swap it out. @@ -776,16 +760,27 @@ retry: if ((action & VM_SWAP_NORMAL) || ((action & VM_SWAP_IDLE) && (minslptime > swap_idle_threshold2))) { - sx_sunlock(&allproc_lock); swapout(p); - vmspace_free(vm); didswap++; + + /* + * swapout() unlocks a proc lock. This is + * ugly, but avoids superfluous lock. + */ + mtx_unlock_spin(&sched_lock); + vm_map_unlock(&vm->vm_map); + vmspace_free(vm); + sx_sunlock(&allproc_lock); goto retry; } - PROC_UNLOCK(p); - vmspace_free(vm); } nextproc: + mtx_unlock_spin(&sched_lock); +nextproc2: + PROC_UNLOCK(p); + vm_map_unlock(&vm->vm_map); +nextproc1: + vmspace_free(vm); continue; } sx_sunlock(&allproc_lock); @@ -804,23 +799,30 @@ swapout(p) struct thread *td; PROC_LOCK_ASSERT(p, MA_OWNED); + mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); #if defined(SWAP_DEBUG) printf("swapping out %d\n", p->p_pid); #endif - mtx_lock_spin(&sched_lock); /* + * The states of this process and its threads may have changed + * by now. Assuming that there is only one pageout daemon thread, + * this process should still be in memory. + */ + KASSERT((p->p_sflag & (PS_INMEM|PS_SWAPPING|PS_SWAPPINGIN)) == PS_INMEM, + ("swapout: lost a swapout race?")); + +#if defined(INVARIANTS) + /* * Make sure that all threads are safe to be swapped out. * * Alternatively, we could swap out only safe threads. */ FOREACH_THREAD_IN_PROC(p, td) { - if (!(td->td_state == TDS_SLP || - td->td_state == TDS_RUNQ)) { - mtx_unlock_spin(&sched_lock); - return; - } + KASSERT(thread_safetoswapout(td), + ("swapout: there is a thread not safe for swapout")); } +#endif /* INVARIANTS */ ++p->p_stats->p_ru.ru_nswap; /* @@ -828,14 +830,14 @@ swapout(p) */ p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); - p->p_sflag &= ~PS_INMEM; - p->p_sflag |= PS_SWAPPING; PROC_UNLOCK(p); FOREACH_THREAD_IN_PROC (p, td) if (td->td_state == TDS_RUNQ) { /* XXXKSE */ remrunqueue(td); /* XXXKSE */ td->td_state = TDS_SWAPPED; } + p->p_sflag &= ~PS_INMEM; + p->p_sflag |= PS_SWAPPING; mtx_unlock_spin(&sched_lock); vm_proc_swapout(p); @@ -844,6 +846,5 @@ swapout(p) mtx_lock_spin(&sched_lock); p->p_sflag &= ~PS_SWAPPING; p->p_swtime = 0; - mtx_unlock_spin(&sched_lock); } #endif /* !NO_SWAPPING */ |