diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-iocost.c | 66 |
1 files changed, 35 insertions, 31 deletions
diff --git a/block/blk-iocost.c b/block/blk-iocost.c index ef9476fca1d8..bbf30bb06c07 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -1979,6 +1979,40 @@ static void transfer_surpluses(struct list_head *surpluses, struct ioc_now *now) list_del_init(&iocg->walk_list); } +/* + * A low weight iocg can amass a large amount of debt, for example, when + * anonymous memory gets reclaimed aggressively. If the system has a lot of + * memory paired with a slow IO device, the debt can span multiple seconds or + * more. If there are no other subsequent IO issuers, the in-debt iocg may end + * up blocked paying its debt while the IO device is idle. + * + * The following protects against such cases. If the device has been + * sufficiently idle for a while, the debts are halved. + */ +static void ioc_forgive_debts(struct ioc *ioc, u64 usage_us_sum, int nr_debtors, + int nr_shortages, struct ioc_now *now) +{ + if (nr_shortages || + div64_u64(100 * usage_us_sum, now->now - ioc->period_at) >= + DEBT_BUSY_USAGE_PCT) + ioc->debt_busy_at = now->now; + + if (nr_debtors && + now->now - ioc->debt_busy_at >= DEBT_REDUCTION_IDLE_DUR) { + struct ioc_gq *iocg; + + list_for_each_entry(iocg, &ioc->active_iocgs, active_list) { + if (iocg->abs_vdebt) { + spin_lock(&iocg->waitq.lock); + iocg->abs_vdebt /= 2; + iocg_kick_waitq(iocg, true, now); + spin_unlock(&iocg->waitq.lock); + } + } + ioc->debt_busy_at = now->now; + } +} + static void ioc_timer_fn(struct timer_list *timer) { struct ioc *ioc = container_of(timer, struct ioc, timer); @@ -2171,37 +2205,7 @@ static void ioc_timer_fn(struct timer_list *timer) list_for_each_entry_safe(iocg, tiocg, &surpluses, surplus_list) list_del_init(&iocg->surplus_list); - /* - * A low weight iocg can amass a large amount of debt, for example, when - * anonymous memory gets reclaimed aggressively. If the system has a lot - * of memory paired with a slow IO device, the debt can span multiple - * seconds or more. If there are no other subsequent IO issuers, the - * in-debt iocg may end up blocked paying its debt while the IO device - * is idle. - * - * The following protects against such pathological cases. If the device - * has been sufficiently idle for a substantial amount of time, the - * debts are halved. The criteria are on the conservative side as we - * want to resolve the rare extreme cases without impacting regular - * operation by forgiving debts too readily. - */ - if (nr_shortages || - div64_u64(100 * usage_us_sum, now.now - ioc->period_at) >= - DEBT_BUSY_USAGE_PCT) - ioc->debt_busy_at = now.now; - - if (nr_debtors && - now.now - ioc->debt_busy_at >= DEBT_REDUCTION_IDLE_DUR) { - list_for_each_entry(iocg, &ioc->active_iocgs, active_list) { - if (iocg->abs_vdebt) { - spin_lock(&iocg->waitq.lock); - iocg->abs_vdebt /= 2; - iocg_kick_waitq(iocg, true, &now); - spin_unlock(&iocg->waitq.lock); - } - } - ioc->debt_busy_at = now.now; - } + ioc_forgive_debts(ioc, usage_us_sum, nr_debtors, nr_shortages, &now); /* * If q is getting clogged or we're missing too much, we're issuing |