Author: kib Date: Mon Aug 13 16:48:46 2018 New Revision: 337714 URL: https://svnweb.freebsd.org/changeset/base/337714
Log: Prevent some parallel swap-ins, rate-limit swapper swap-ins. If faultin() was called outside swapper (from PHOLD()), do not allow swapper to initiate additional swap-ins. Swapper' initiated swap-ins are serialized because they are synchronous and executed in the context of the thread0. With the added limitation, we only allow parallel swap-ins from PHOLD(), which is up to PHOLD() users to manage, usually they do not need to. Rate-limit swapper' swap-ins to one in the MAXSLP / 2 seconds interval, counting faultin() swapins. Suggested by: alc Reviewed by: alc, markj Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Differential revision: https://reviews.freebsd.org/D16610 Modified: head/sys/vm/vm_swapout.c Modified: head/sys/vm/vm_swapout.c ============================================================================== --- head/sys/vm/vm_swapout.c Mon Aug 13 16:26:26 2018 (r337713) +++ head/sys/vm/vm_swapout.c Mon Aug 13 16:48:46 2018 (r337714) @@ -159,6 +159,8 @@ static struct mtx vm_daemon_mtx; MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); static int swapped_cnt; +static int swap_inprogress; /* Pending swap-ins done outside swapper. */ +static int last_swapin; static void swapclear(struct proc *); static int swapout(struct proc *); @@ -634,6 +636,8 @@ faultin(struct proc *p) sx_xlock(&allproc_lock); MPASS(swapped_cnt > 0); swapped_cnt--; + if (curthread != &thread0) + swap_inprogress++; sx_xunlock(&allproc_lock); /* @@ -644,6 +648,13 @@ faultin(struct proc *p) FOREACH_THREAD_IN_PROC(p, td) vm_thread_swapin(td, oom_alloc); + if (curthread != &thread0) { + sx_xlock(&allproc_lock); + MPASS(swap_inprogress > 0); + swap_inprogress--; + last_swapin = ticks; + sx_xunlock(&allproc_lock); + } PROC_LOCK(p); swapclear(p); p->p_swtick = ticks; @@ -661,18 +672,17 @@ faultin(struct proc *p) */ static struct proc * -swapper_selector(void) +swapper_selector(bool wkilled_only) { struct proc *p, *res; struct thread *td; - int min_flag, ppri, pri, slptime, swtime; + int ppri, pri, slptime, swtime; sx_assert(&allproc_lock, SA_SLOCKED); if (swapped_cnt == 0) return (NULL); res = NULL; ppri = INT_MIN; - min_flag = vm_page_count_min(); FOREACH_PROC_IN_SYSTEM(p) { PROC_LOCK(p); if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT | @@ -690,7 +700,7 @@ swapper_selector(void) */ return (p); } - if (min_flag) { + if (wkilled_only) { PROC_UNLOCK(p); continue; } @@ -721,11 +731,29 @@ swapper_selector(void) } PROC_UNLOCK(p); } + if (res != NULL) PROC_LOCK(res); return (res); } +#define SWAPIN_INTERVAL (MAXSLP * hz / 2) + +/* + * Limit swapper to swap in one non-WKILLED process in MAXSLP/2 + * interval, assuming that there is: + * - no memory shortage; + * - no parallel swap-ins; + * - no other swap-ins in the current SWAPIN_INTERVAL. + */ +static bool +swapper_wkilled_only(void) +{ + + return (vm_page_count_min() || swap_inprogress > 0 || + (u_int)(ticks - last_swapin) < SWAPIN_INTERVAL); +} + void swapper(void) { @@ -733,11 +761,11 @@ swapper(void) for (;;) { sx_slock(&allproc_lock); - p = swapper_selector(); + p = swapper_selector(swapper_wkilled_only()); sx_sunlock(&allproc_lock); if (p == NULL) { - tsleep(&proc0, PVM, "swapin", MAXSLP * hz / 2); + tsleep(&proc0, PVM, "swapin", SWAPIN_INTERVAL); } else { PROC_LOCK_ASSERT(p, MA_OWNED); _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
