Commit 69d7fde5 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

blkcg: use CGROUP_WEIGHT_* scale for io.weight on the unified hierarchy 



cgroup is trying to make interface consistent across different
controllers.  For weight based resource control, the knob should have
the range [1, 10000] and default to 100.  This patch updates
cfq-iosched so that the weight range conforms.  The internal
calculations have enough range and the widening of the weight range
shouldn't cause any problem.

* blkcg_policy->cpd_bind_fn() is added.  If present, this is invoked
  when blkcg is attached to a hierarchy.

* cfq_cpd_init() is updated to use the new default value on the
  unified hierarchy.

* cfq_cpd_bind() callback is implemented to clear per-blkg configs and
  apply the default config matching the hierarchy type.

* cfqd->root_group->[leaf_]weight initialization in cfq_init_queue()
  is moved into !CONFIG_CFQ_GROUP_IOSCHED block.  cfq_cpd_bind() is
  now responsible for initializing the initial weights when blkcg is
  enabled.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 3ecca629

Documentation/cgroups/unified-hierarchy.txt

+1 −1
Original line number Diff line number Diff line
@@ -464,7 +464,7 @@ may be specified in any order and not all pairs have to be specified. 


	The weight setting, currently only available and effective if

	cfq-iosched is in use for the target device.  The weight is

	between 10 and 1000 and defaults to 500.  The first line

	between 1 and 10000 and defaults to 100.  The first line

	always contains the default weight in the following format to

	use when per-device setting is missing.

block/blk-cgroup.c

+21 −0
Original line number Diff line number Diff line
@@ -1143,11 +1143,32 @@ static int blkcg_can_attach(struct cgroup_subsys_state *css, 
	return ret;

}



static void blkcg_bind(struct cgroup_subsys_state *root_css)

{

	int i;



	mutex_lock(&blkcg_pol_mutex);



	for (i = 0; i < BLKCG_MAX_POLS; i++) {

		struct blkcg_policy *pol = blkcg_policy[i];

		struct blkcg *blkcg;



		if (!pol || !pol->cpd_bind_fn)

			continue;



		list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node)

			if (blkcg->cpd[pol->plid])

				pol->cpd_bind_fn(blkcg->cpd[pol->plid]);

	}

	mutex_unlock(&blkcg_pol_mutex);

}



struct cgroup_subsys io_cgrp_subsys = {

	.css_alloc = blkcg_css_alloc,

	.css_offline = blkcg_css_offline,

	.css_free = blkcg_css_free,

	.can_attach = blkcg_can_attach,

	.bind = blkcg_bind,

	.dfl_cftypes = blkcg_files,

	.legacy_cftypes = blkcg_legacy_files,

	.legacy_name = "blkio",

block/cfq-iosched.c

+40 −15
Original line number Diff line number Diff line
@@ -1522,6 +1522,9 @@ static void cfq_init_cfqg_base(struct cfq_group *cfqg) 
}



#ifdef CONFIG_CFQ_GROUP_IOSCHED

static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,

			    bool on_dfl, bool reset_dev, bool is_leaf_weight);



static void cfqg_stats_exit(struct cfqg_stats *stats)

{

	blkg_rwstat_exit(&stats->merged);
@@ -1578,14 +1581,14 @@ static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp) 
static void cfq_cpd_init(struct blkcg_policy_data *cpd)

{

	struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);

	unsigned int weight = cgroup_on_dfl(blkcg_root.css.cgroup) ?

			      CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;



	if (cpd_to_blkcg(cpd) == &blkcg_root) {

		cgd->weight = 2 * CFQ_WEIGHT_LEGACY_DFL;

		cgd->leaf_weight = 2 * CFQ_WEIGHT_LEGACY_DFL;

	} else {

		cgd->weight = CFQ_WEIGHT_LEGACY_DFL;

		cgd->leaf_weight = CFQ_WEIGHT_LEGACY_DFL;

	}

	if (cpd_to_blkcg(cpd) == &blkcg_root)

		weight *= 2;



	cgd->weight = weight;

	cgd->leaf_weight = weight;

}



static void cfq_cpd_free(struct blkcg_policy_data *cpd)
@@ -1593,6 +1596,19 @@ static void cfq_cpd_free(struct blkcg_policy_data *cpd) 
	kfree(cpd_to_cfqgd(cpd));

}



static void cfq_cpd_bind(struct blkcg_policy_data *cpd)

{

	struct blkcg *blkcg = cpd_to_blkcg(cpd);

	bool on_dfl = cgroup_on_dfl(blkcg_root.css.cgroup);

	unsigned int weight = on_dfl ? CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;



	if (blkcg == &blkcg_root)

		weight *= 2;



	WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, false));

	WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, true));

}



static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)

{

	struct cfq_group *cfqg;
@@ -1742,6 +1758,8 @@ static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of, 
					char *buf, size_t nbytes, loff_t off,

					bool on_dfl, bool is_leaf_weight)

{

	unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;

	unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;

	struct blkcg *blkcg = css_to_blkcg(of_css(of));

	struct blkg_conf_ctx ctx;

	struct cfq_group *cfqg;
@@ -1769,7 +1787,7 @@ static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of, 
	cfqgd = blkcg_to_cfqgd(blkcg);



	ret = -ERANGE;

	if (!v || (v >= CFQ_WEIGHT_LEGACY_MIN && v <= CFQ_WEIGHT_LEGACY_MAX)) {

	if (!v || (v >= min && v <= max)) {

		if (!is_leaf_weight) {

			cfqg->dev_weight = v;

			cfqg->new_weight = v ?: cfqgd->weight;
@@ -1797,15 +1815,17 @@ static ssize_t cfqg_set_leaf_weight_device(struct kernfs_open_file *of, 
}



static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,

			    bool is_leaf_weight)

			    bool on_dfl, bool reset_dev, bool is_leaf_weight)

{

	unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;

	unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;

	struct blkcg *blkcg = css_to_blkcg(css);

	struct blkcg_gq *blkg;

	struct cfq_group_data *cfqgd;

	int ret = 0;



	if (val < CFQ_WEIGHT_LEGACY_MIN || val > CFQ_WEIGHT_LEGACY_MAX)

		return -EINVAL;

	if (val < min || val > max)

		return -ERANGE;



	spin_lock_irq(&blkcg->lock);

	cfqgd = blkcg_to_cfqgd(blkcg);
@@ -1826,9 +1846,13 @@ static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val, 
			continue;



		if (!is_leaf_weight) {

			if (reset_dev)

				cfqg->dev_weight = 0;

			if (!cfqg->dev_weight)

				cfqg->new_weight = cfqgd->weight;

		} else {

			if (reset_dev)

				cfqg->dev_leaf_weight = 0;

			if (!cfqg->dev_leaf_weight)

				cfqg->new_leaf_weight = cfqgd->leaf_weight;

		}
@@ -1842,13 +1866,13 @@ out: 
static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,

			  u64 val)

{

	return __cfq_set_weight(css, val, false);

	return __cfq_set_weight(css, val, false, false, false);

}



static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,

			       struct cftype *cft, u64 val)

{

	return __cfq_set_weight(css, val, true);

	return __cfq_set_weight(css, val, false, false, true);

}



static int cfqg_print_stat(struct seq_file *sf, void *v)
@@ -2135,7 +2159,7 @@ static ssize_t cfq_set_weight_on_dfl(struct kernfs_open_file *of, 
	/* "WEIGHT" or "default WEIGHT" sets the default weight */

	v = simple_strtoull(buf, &endp, 0);

	if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {

		ret = __cfq_set_weight(of_css(of), v, false);

		ret = __cfq_set_weight(of_css(of), v, true, false, false);

		return ret ?: nbytes;

	}
@@ -4512,9 +4536,9 @@ static int cfq_init_queue(struct request_queue *q, struct elevator_type *e) 
		goto out_free;



	cfq_init_cfqg_base(cfqd->root_group);

#endif

	cfqd->root_group->weight = 2 * CFQ_WEIGHT_LEGACY_DFL;

	cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_LEGACY_DFL;

#endif



	/*

	 * Not strictly needed (since RB_ROOT just clears the node and we
@@ -4715,6 +4739,7 @@ static struct blkcg_policy blkcg_policy_cfq = { 
	.cpd_alloc_fn		= cfq_cpd_alloc,

	.cpd_init_fn		= cfq_cpd_init,

	.cpd_free_fn		= cfq_cpd_free,

	.cpd_bind_fn		= cfq_cpd_bind,



	.pd_alloc_fn		= cfq_pd_alloc,

	.pd_init_fn		= cfq_pd_init,

include/linux/blk-cgroup.h

+2 −0
Original line number Diff line number Diff line
@@ -138,6 +138,7 @@ struct blkcg_gq { 
typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);

typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);

typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);

typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);

typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp, int node);

typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);

typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
@@ -155,6 +156,7 @@ struct blkcg_policy { 
	blkcg_pol_alloc_cpd_fn		*cpd_alloc_fn;

	blkcg_pol_init_cpd_fn		*cpd_init_fn;

	blkcg_pol_free_cpd_fn		*cpd_free_fn;

	blkcg_pol_bind_cpd_fn		*cpd_bind_fn;



	blkcg_pol_alloc_pd_fn		*pd_alloc_fn;

	blkcg_pol_init_pd_fn		*pd_init_fn;

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