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Date: Sun, 2 Aug 2015 16:23:44 -0400
From: Tejun Heo <tj@...nel.org>
To: axboe@...nel.dk, hannes@...xchg.org, lizefan@...wei.com
Cc: linux-kernel@...r.kernel.org, vgoyal@...hat.com,
avanzini.arianna@...il.com, cgroups@...r.kernel.org,
kernel-team@...com, Tejun Heo <tj@...nel.org>
Subject: [PATCH 4/4] 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: Tejun Heo <tj@...nel.org>
Cc: Vivek Goyal <vgoyal@...hat.com>
Cc: Arianna Avanzini <avanzini.arianna@...il.com>
---
Documentation/cgroups/unified-hierarchy.txt | 2 +-
block/blk-cgroup.c | 21 +++++++++++
block/cfq-iosched.c | 55 +++++++++++++++++++++--------
include/linux/blk-cgroup.h | 2 ++
4 files changed, 64 insertions(+), 16 deletions(-)
diff --git a/Documentation/cgroups/unified-hierarchy.txt b/Documentation/cgroups/unified-hierarchy.txt
index ee6ce34..bd319f0 100644
--- a/Documentation/cgroups/unified-hierarchy.txt
+++ b/Documentation/cgroups/unified-hierarchy.txt
@@ -459,7 +459,7 @@ 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.
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 88bdb73..ac8370c 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -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",
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 0fe721e..04de884 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -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,
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 9a7c4bd..0a5cc7a 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -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;
--
2.4.3
--
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