Commit bd0adb91 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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blk-iocost: use WEIGHT_ONE based fixed point number for weights 



To improve weight donations, we want to able to scale inuse with a greater
accuracy and down below 1. Let's make non-hierarchical weights to use
WEIGHT_ONE based fixed point numbers too like hierarchical ones.

This doesn't cause any behavior changes yet.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent fe20cdb5

block/blk-iocost.c

+13 −12
Original line number Diff line number Diff line
@@ -984,8 +984,8 @@ static void current_hweight(struct ioc_gq *iocg, u32 *hw_activep, u32 *hw_inusep 
	for (lvl = 0; lvl <= iocg->level - 1; lvl++) {

		struct ioc_gq *parent = iocg->ancestors[lvl];

		struct ioc_gq *child = iocg->ancestors[lvl + 1];

		u32 active_sum = READ_ONCE(parent->child_active_sum);

		u32 inuse_sum = READ_ONCE(parent->child_inuse_sum);

		u64 active_sum = READ_ONCE(parent->child_active_sum);

		u64 inuse_sum = READ_ONCE(parent->child_inuse_sum);

		u32 active = READ_ONCE(child->active);

		u32 inuse = READ_ONCE(child->inuse);
@@ -993,11 +993,11 @@ static void current_hweight(struct ioc_gq *iocg, u32 *hw_activep, u32 *hw_inusep 
		if (!active_sum || !inuse_sum)

			continue;



		active_sum = max(active, active_sum);

		hwa = hwa * active / active_sum;	/* max 16bits * 10000 */

		active_sum = max_t(u64, active, active_sum);

		hwa = div64_u64((u64)hwa * active, active_sum);



		inuse_sum = max(inuse, inuse_sum);

		hwi = hwi * inuse / inuse_sum;		/* max 16bits * 10000 */

		inuse_sum = max_t(u64, inuse, inuse_sum);

		hwi = div64_u64((u64)hwi * inuse, inuse_sum);

	}



	iocg->hweight_active = max_t(u32, hwa, 1);
@@ -1022,7 +1022,8 @@ static void weight_updated(struct ioc_gq *iocg) 
	weight = iocg->cfg_weight ?: iocc->dfl_weight;

	if (weight != iocg->weight && iocg->active)

		propagate_weights(iocg, weight,

			DIV64_U64_ROUND_UP(iocg->inuse * weight, iocg->weight));

				  DIV64_U64_ROUND_UP((u64)iocg->inuse * weight,

						     iocg->weight));

	iocg->weight = weight;

}
@@ -2050,7 +2051,7 @@ static struct blkcg_policy_data *ioc_cpd_alloc(gfp_t gfp) 
	if (!iocc)

		return NULL;



	iocc->dfl_weight = CGROUP_WEIGHT_DFL;

	iocc->dfl_weight = CGROUP_WEIGHT_DFL * WEIGHT_ONE;

	return &iocc->cpd;

}
@@ -2136,7 +2137,7 @@ static u64 ioc_weight_prfill(struct seq_file *sf, struct blkg_policy_data *pd, 
	struct ioc_gq *iocg = pd_to_iocg(pd);



	if (dname && iocg->cfg_weight)

		seq_printf(sf, "%s %u\n", dname, iocg->cfg_weight);

		seq_printf(sf, "%s %u\n", dname, iocg->cfg_weight / WEIGHT_ONE);

	return 0;

}
@@ -2146,7 +2147,7 @@ static int ioc_weight_show(struct seq_file *sf, void *v) 
	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));

	struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg);



	seq_printf(sf, "default %u\n", iocc->dfl_weight);

	seq_printf(sf, "default %u\n", iocc->dfl_weight / WEIGHT_ONE);

	blkcg_print_blkgs(sf, blkcg, ioc_weight_prfill,

			  &blkcg_policy_iocost, seq_cft(sf)->private, false);

	return 0;
@@ -2172,7 +2173,7 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf, 
			return -EINVAL;



		spin_lock(&blkcg->lock);

		iocc->dfl_weight = v;

		iocc->dfl_weight = v * WEIGHT_ONE;

		hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {

			struct ioc_gq *iocg = blkg_to_iocg(blkg);
@@ -2203,7 +2204,7 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf, 
	}



	spin_lock(&iocg->ioc->lock);

	iocg->cfg_weight = v;

	iocg->cfg_weight = v * WEIGHT_ONE;

	weight_updated(iocg);

	spin_unlock(&iocg->ioc->lock);

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