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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: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2020-09-01 14:52:39 -04:00 committed by Jens Axboe
parent fe20cdb516
commit bd0adb91a6
1 changed files with 13 additions and 12 deletions
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25
block/blk-iocost.c
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@ -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);