Commit 8692d2db authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

blk-iocost: replace iocg->has_surplus with ->surplus_list 



Instead of marking iocgs with surplus with a flag and filtering for them
while walking all active iocgs, build a surpluses list. This doesn't make
much difference now but will help implementing improved donation logic which
will iterate iocgs with surplus multiple times.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 1aa50d02

block/blk-iocost.c

+11 −8
Original line number Diff line number Diff line
@@ -494,9 +494,9 @@ struct ioc_gq { 
	int				hweight_gen;

	u32				hweight_active;

	u32				hweight_inuse;

	bool				has_surplus;



	struct list_head		walk_list;

	struct list_head		surplus_list;



	struct wait_queue_head		waitq;

	struct hrtimer			waitq_timer;
@@ -1507,6 +1507,7 @@ static void ioc_timer_fn(struct timer_list *timer) 
	struct ioc *ioc = container_of(timer, struct ioc, timer);

	struct ioc_gq *iocg, *tiocg;

	struct ioc_now now;

	LIST_HEAD(surpluses);

	int nr_surpluses = 0, nr_shortages = 0, nr_lagging = 0;

	u32 ppm_rthr = MILLION - ioc->params.qos[QOS_RPPM];

	u32 ppm_wthr = MILLION - ioc->params.qos[QOS_WPPM];
@@ -1630,8 +1631,7 @@ static void ioc_timer_fn(struct timer_list *timer) 
		/* see whether there's surplus vtime */

		vmin = now.vnow - ioc->margins.max;



		iocg->has_surplus = false;



		WARN_ON_ONCE(!list_empty(&iocg->surplus_list));

		if (!waitqueue_active(&iocg->waitq) &&

		    time_before64(vtime, vmin)) {

			u64 delta = vmin - vtime;
@@ -1641,7 +1641,7 @@ static void ioc_timer_fn(struct timer_list *timer) 
			atomic64_add(delta, &iocg->done_vtime);

			/* if usage is sufficiently low, maybe it can donate */

			if (surplus_adjusted_hweight_inuse(usage, hw_inuse)) {

				iocg->has_surplus = true;

				list_add(&iocg->surplus_list, &surpluses);

				nr_surpluses++;

			}

		} else if (hw_inuse < hw_active) {
@@ -1677,13 +1677,10 @@ static void ioc_timer_fn(struct timer_list *timer) 
		goto skip_surplus_transfers;



	/* there are both shortages and surpluses, transfer surpluses */

	list_for_each_entry(iocg, &ioc->active_iocgs, active_list) {

	list_for_each_entry(iocg, &surpluses, surplus_list) {

		u32 usage, hw_active, hw_inuse, new_hwi, new_inuse;

		int nr_valid = 0;



		if (!iocg->has_surplus)

			continue;



		/* base the decision on max historical usage */

		for (i = 0, usage = 0; i < NR_USAGE_SLOTS; i++) {

			if (iocg->usages[i]) {
@@ -1711,6 +1708,10 @@ static void ioc_timer_fn(struct timer_list *timer) 
skip_surplus_transfers:

	commit_weights(ioc);



	/* surplus list should be dissolved after use */

	list_for_each_entry_safe(iocg, tiocg, &surpluses, surplus_list)

		list_del_init(&iocg->surplus_list);



	/*

	 * If q is getting clogged or we're missing too much, we're issuing

	 * too much IO and should lower vtime rate.  If we're not missing
@@ -2284,6 +2285,7 @@ static void ioc_pd_init(struct blkg_policy_data *pd) 
	atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period));

	INIT_LIST_HEAD(&iocg->active_list);

	INIT_LIST_HEAD(&iocg->walk_list);

	INIT_LIST_HEAD(&iocg->surplus_list);

	iocg->hweight_active = WEIGHT_ONE;

	iocg->hweight_inuse = WEIGHT_ONE;
@@ -2320,6 +2322,7 @@ static void ioc_pd_free(struct blkg_policy_data *pd) 
		}



		WARN_ON_ONCE(!list_empty(&iocg->walk_list));

		WARN_ON_ONCE(!list_empty(&iocg->surplus_list));



		spin_unlock_irqrestore(&ioc->lock, flags);

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