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

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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: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Tejun Heo 2015-08-18 14:55:36 -07:00 committed by Jens Axboe
parent 3ecca62931
commit 69d7fde590
4 changed files with 64 additions and 16 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
Documentation/cgroups/unified-hierarchy.txt
View file

@ -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.

21
block/blk-cgroup.c
View file

@ -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",

55
block/cfq-iosched.c
View file

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

2
include/linux/blk-cgroup.h
View file

@ -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;