[PATCH 17/21] blkcg: move blkio_group_stats_cpu and friends to blk-throttle.c
Tejun Heo
tj at kernel.org
Wed Mar 28 22:51:27 UTC 2012
blkio_group_stats_cpu is used only by blk-throtl and has no reason to
be defined in blkcg core.
* Move blkio_group_stats_cpu to blk-throttle.c and rename it to
tg_stats_cpu.
* blkg_policy_data->stats_cpu is replaced with throtl_grp->stats_cpu.
prfill functions updated accordingly.
* All related macros / functions are renamed so that they have tg_
prefix and the unnecessary @pol arguments are dropped.
* Per-cpu stats allocation code is also moved from blk-cgroup.c to
blk-throttle.c and gets simplified to only deal with
BLKIO_POLICY_THROTL. percpu stat free is performed by the exit
method throtl_exit_blkio_group().
* throtl_reset_group_stats() implemented for
blkio_reset_group_stats_fn method so that tg->stats_cpu can be
reset.
Signed-off-by: Tejun Heo <tj at kernel.org>
---
block/blk-cgroup.c | 98 +--------------------------------------
block/blk-cgroup.h | 13 -----
block/blk-throttle.c | 128 ++++++++++++++++++++++++++++++++++++++++++++------
3 files changed, 114 insertions(+), 125 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index d7c7f17..0b4b765 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -30,13 +30,6 @@ static LIST_HEAD(blkio_list);
static DEFINE_MUTEX(all_q_mutex);
static LIST_HEAD(all_q_list);
-/* List of groups pending per cpu stats allocation */
-static DEFINE_SPINLOCK(alloc_list_lock);
-static LIST_HEAD(alloc_list);
-
-static void blkio_stat_alloc_fn(struct work_struct *);
-static DECLARE_DELAYED_WORK(blkio_stat_alloc_work, blkio_stat_alloc_fn);
-
struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
EXPORT_SYMBOL_GPL(blkio_root_cgroup);
@@ -63,60 +56,6 @@ struct blkio_cgroup *bio_blkio_cgroup(struct bio *bio)
}
EXPORT_SYMBOL_GPL(bio_blkio_cgroup);
-/*
- * Worker for allocating per cpu stat for blk groups. This is scheduled on
- * the system_nrt_wq once there are some groups on the alloc_list waiting
- * for allocation.
- */
-static void blkio_stat_alloc_fn(struct work_struct *work)
-{
- static void *pcpu_stats[BLKIO_NR_POLICIES];
- struct delayed_work *dwork = to_delayed_work(work);
- struct blkio_group *blkg;
- int i;
- bool empty = false;
-
-alloc_stats:
- for (i = 0; i < BLKIO_NR_POLICIES; i++) {
- if (pcpu_stats[i] != NULL)
- continue;
-
- pcpu_stats[i] = alloc_percpu(struct blkio_group_stats_cpu);
-
- /* Allocation failed. Try again after some time. */
- if (pcpu_stats[i] == NULL) {
- queue_delayed_work(system_nrt_wq, dwork,
- msecs_to_jiffies(10));
- return;
- }
- }
-
- spin_lock_irq(&blkio_list_lock);
- spin_lock(&alloc_list_lock);
-
- /* cgroup got deleted or queue exited. */
- if (!list_empty(&alloc_list)) {
- blkg = list_first_entry(&alloc_list, struct blkio_group,
- alloc_node);
- for (i = 0; i < BLKIO_NR_POLICIES; i++) {
- struct blkg_policy_data *pd = blkg->pd[i];
-
- if (blkio_policy[i] && pd && !pd->stats_cpu)
- swap(pd->stats_cpu, pcpu_stats[i]);
- }
-
- list_del_init(&blkg->alloc_node);
- }
-
- empty = list_empty(&alloc_list);
-
- spin_unlock(&alloc_list_lock);
- spin_unlock_irq(&blkio_list_lock);
-
- if (!empty)
- goto alloc_stats;
-}
-
/**
* blkg_free - free a blkg
* @blkg: blkg to free
@@ -140,7 +79,6 @@ static void blkg_free(struct blkio_group *blkg)
if (pol && pol->ops.blkio_exit_group_fn)
pol->ops.blkio_exit_group_fn(blkg);
- free_percpu(pd->stats_cpu);
kfree(pd);
}
@@ -167,7 +105,6 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg,
blkg->q = q;
INIT_LIST_HEAD(&blkg->q_node);
- INIT_LIST_HEAD(&blkg->alloc_node);
blkg->blkcg = blkcg;
blkg->refcnt = 1;
cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
@@ -245,12 +182,6 @@ struct blkio_group *blkg_lookup_create(struct blkio_cgroup *blkcg,
hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
list_add(&blkg->q_node, &q->blkg_list);
spin_unlock(&blkcg->lock);
-
- spin_lock(&alloc_list_lock);
- list_add(&blkg->alloc_node, &alloc_list);
- /* Queue per cpu stat allocation from worker thread. */
- queue_delayed_work(system_nrt_wq, &blkio_stat_alloc_work, 0);
- spin_unlock(&alloc_list_lock);
out:
return blkg;
}
@@ -284,10 +215,6 @@ static void blkg_destroy(struct blkio_group *blkg)
list_del_init(&blkg->q_node);
hlist_del_init_rcu(&blkg->blkcg_node);
- spin_lock(&alloc_list_lock);
- list_del_init(&blkg->alloc_node);
- spin_unlock(&alloc_list_lock);
-
/*
* Put the reference taken at the time of creation so that when all
* queues are gone, group can be destroyed.
@@ -319,9 +246,6 @@ void update_root_blkg_pd(struct request_queue *q, enum blkio_policy_id plid)
pd = kzalloc(sizeof(*pd) + pol->pdata_size, GFP_KERNEL);
WARN_ON_ONCE(!pd);
- pd->stats_cpu = alloc_percpu(struct blkio_group_stats_cpu);
- WARN_ON_ONCE(!pd->stats_cpu);
-
blkg->pd[plid] = pd;
pd->blkg = blkg;
pol->ops.blkio_init_group_fn(blkg);
@@ -381,23 +305,6 @@ void __blkg_release(struct blkio_group *blkg)
}
EXPORT_SYMBOL_GPL(__blkg_release);
-static void blkio_reset_stats_cpu(struct blkio_group *blkg, int plid)
-{
- struct blkg_policy_data *pd = blkg->pd[plid];
- int cpu;
-
- if (pd->stats_cpu == NULL)
- return;
-
- for_each_possible_cpu(cpu) {
- struct blkio_group_stats_cpu *sc =
- per_cpu_ptr(pd->stats_cpu, cpu);
-
- blkg_rwstat_reset(&sc->service_bytes);
- blkg_rwstat_reset(&sc->serviced);
- }
-}
-
static int
blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
{
@@ -416,12 +323,9 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
struct blkio_policy_type *pol;
- list_for_each_entry(pol, &blkio_list, list) {
- blkio_reset_stats_cpu(blkg, pol->plid);
-
+ list_for_each_entry(pol, &blkio_list, list)
if (pol->ops.blkio_reset_group_stats_fn)
pol->ops.blkio_reset_group_stats_fn(blkg);
- }
}
spin_unlock_irq(&blkcg->lock);
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 791570394..e368dd00 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -64,14 +64,6 @@ struct blkg_rwstat {
uint64_t cnt[BLKG_RWSTAT_NR];
};
-/* Per cpu blkio group stats */
-struct blkio_group_stats_cpu {
- /* total bytes transferred */
- struct blkg_rwstat service_bytes;
- /* total IOs serviced, post merge */
- struct blkg_rwstat serviced;
-};
-
struct blkio_group_conf {
unsigned int weight;
u64 iops[2];
@@ -86,9 +78,6 @@ struct blkg_policy_data {
/* Configuration */
struct blkio_group_conf conf;
- /* Per cpu stats pointer */
- struct blkio_group_stats_cpu __percpu *stats_cpu;
-
/* pol->pdata_size bytes of private data used by policy impl */
char pdata[] __aligned(__alignof__(unsigned long long));
};
@@ -106,8 +95,6 @@ struct blkio_group {
struct blkg_policy_data *pd[BLKIO_NR_POLICIES];
- /* List of blkg waiting for per cpu stats memory to be allocated */
- struct list_head alloc_node;
struct rcu_head rcu_head;
};
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index cb259bc..27f7960 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -40,6 +40,14 @@ struct throtl_rb_root {
#define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
+/* Per-cpu group stats */
+struct tg_stats_cpu {
+ /* total bytes transferred */
+ struct blkg_rwstat service_bytes;
+ /* total IOs serviced, post merge */
+ struct blkg_rwstat serviced;
+};
+
struct throtl_grp {
/* active throtl group service_tree member */
struct rb_node rb_node;
@@ -76,6 +84,12 @@ struct throtl_grp {
/* Some throttle limits got updated for the group */
int limits_changed;
+
+ /* Per cpu stats pointer */
+ struct tg_stats_cpu __percpu *stats_cpu;
+
+ /* List of tgs waiting for per cpu stats memory to be allocated */
+ struct list_head stats_alloc_node;
};
struct throtl_data
@@ -100,6 +114,13 @@ struct throtl_data
int limits_changed;
};
+/* list and work item to allocate percpu group stats */
+static DEFINE_SPINLOCK(tg_stats_alloc_lock);
+static LIST_HEAD(tg_stats_alloc_list);
+
+static void tg_stats_alloc_fn(struct work_struct *);
+static DECLARE_DELAYED_WORK(tg_stats_alloc_work, tg_stats_alloc_fn);
+
static inline struct throtl_grp *blkg_to_tg(struct blkio_group *blkg)
{
return blkg_to_pdata(blkg, &blkio_policy_throtl);
@@ -142,6 +163,44 @@ static inline unsigned int total_nr_queued(struct throtl_data *td)
return td->nr_queued[0] + td->nr_queued[1];
}
+/*
+ * Worker for allocating per cpu stat for tgs. This is scheduled on the
+ * system_nrt_wq once there are some groups on the alloc_list waiting for
+ * allocation.
+ */
+static void tg_stats_alloc_fn(struct work_struct *work)
+{
+ static struct tg_stats_cpu *stats_cpu; /* this fn is non-reentrant */
+ struct delayed_work *dwork = to_delayed_work(work);
+ bool empty = false;
+
+alloc_stats:
+ if (!stats_cpu) {
+ stats_cpu = alloc_percpu(struct tg_stats_cpu);
+ if (!stats_cpu) {
+ /* allocation failed, try again after some time */
+ queue_delayed_work(system_nrt_wq, dwork,
+ msecs_to_jiffies(10));
+ return;
+ }
+ }
+
+ spin_lock_irq(&tg_stats_alloc_lock);
+
+ if (!list_empty(&tg_stats_alloc_list)) {
+ struct throtl_grp *tg = list_first_entry(&tg_stats_alloc_list,
+ struct throtl_grp,
+ stats_alloc_node);
+ swap(tg->stats_cpu, stats_cpu);
+ list_del_init(&tg->stats_alloc_node);
+ }
+
+ empty = list_empty(&tg_stats_alloc_list);
+ spin_unlock_irq(&tg_stats_alloc_lock);
+ if (!empty)
+ goto alloc_stats;
+}
+
static void throtl_init_blkio_group(struct blkio_group *blkg)
{
struct throtl_grp *tg = blkg_to_tg(blkg);
@@ -155,6 +214,43 @@ static void throtl_init_blkio_group(struct blkio_group *blkg)
tg->bps[WRITE] = -1;
tg->iops[READ] = -1;
tg->iops[WRITE] = -1;
+
+ /*
+ * Ugh... We need to perform per-cpu allocation for tg->stats_cpu
+ * but percpu allocator can't be called from IO path. Queue tg on
+ * tg_stats_alloc_list and allocate from work item.
+ */
+ spin_lock(&tg_stats_alloc_lock);
+ list_add(&tg->stats_alloc_node, &tg_stats_alloc_list);
+ queue_delayed_work(system_nrt_wq, &tg_stats_alloc_work, 0);
+ spin_unlock(&tg_stats_alloc_lock);
+}
+
+static void throtl_exit_blkio_group(struct blkio_group *blkg)
+{
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+
+ spin_lock(&tg_stats_alloc_lock);
+ list_del_init(&tg->stats_alloc_node);
+ spin_unlock(&tg_stats_alloc_lock);
+
+ free_percpu(tg->stats_cpu);
+}
+
+static void throtl_reset_group_stats(struct blkio_group *blkg)
+{
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+ int cpu;
+
+ if (tg->stats_cpu == NULL)
+ return;
+
+ for_each_possible_cpu(cpu) {
+ struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
+
+ blkg_rwstat_reset(&sc->service_bytes);
+ blkg_rwstat_reset(&sc->serviced);
+ }
}
static struct
@@ -565,12 +661,12 @@ static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
static void throtl_update_dispatch_stats(struct blkio_group *blkg, u64 bytes,
int rw)
{
- struct blkg_policy_data *pd = blkg->pd[BLKIO_POLICY_THROTL];
- struct blkio_group_stats_cpu *stats_cpu;
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+ struct tg_stats_cpu *stats_cpu;
unsigned long flags;
/* If per cpu stats are not allocated yet, don't do any accounting. */
- if (pd->stats_cpu == NULL)
+ if (tg->stats_cpu == NULL)
return;
/*
@@ -580,7 +676,7 @@ static void throtl_update_dispatch_stats(struct blkio_group *blkg, u64 bytes,
*/
local_irq_save(flags);
- stats_cpu = this_cpu_ptr(pd->stats_cpu);
+ stats_cpu = this_cpu_ptr(tg->stats_cpu);
blkg_rwstat_add(&stats_cpu->serviced, rw, 1);
blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);
@@ -842,15 +938,15 @@ static void throtl_update_blkio_group_common(struct throtl_data *td,
throtl_schedule_delayed_work(td, 0);
}
-static u64 blkg_prfill_cpu_rwstat(struct seq_file *sf,
- struct blkg_policy_data *pd, int off)
+static u64 tg_prfill_cpu_rwstat(struct seq_file *sf,
+ struct blkg_policy_data *pd, int off)
{
+ struct throtl_grp *tg = (void *)pd->pdata;
struct blkg_rwstat rwstat = { }, tmp;
int i, cpu;
for_each_possible_cpu(cpu) {
- struct blkio_group_stats_cpu *sc =
- per_cpu_ptr(pd->stats_cpu, cpu);
+ struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
tmp = blkg_rwstat_read((void *)sc + off);
for (i = 0; i < BLKG_RWSTAT_NR; i++)
@@ -861,12 +957,12 @@ static u64 blkg_prfill_cpu_rwstat(struct seq_file *sf,
}
/* print per-cpu blkg_rwstat specified by BLKCG_STAT_PRIV() */
-static int blkcg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,
- struct seq_file *sf)
+static int tg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,
+ struct seq_file *sf)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
- blkcg_print_blkgs(sf, blkcg, blkg_prfill_cpu_rwstat,
+ blkcg_print_blkgs(sf, blkcg, tg_prfill_cpu_rwstat,
BLKCG_STAT_POL(cft->private),
BLKCG_STAT_OFF(cft->private), true);
return 0;
@@ -1012,14 +1108,14 @@ static struct cftype throtl_files[] = {
{
.name = "throttle.io_service_bytes",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_THROTL,
- offsetof(struct blkio_group_stats_cpu, service_bytes)),
- .read_seq_string = blkcg_print_cpu_rwstat,
+ offsetof(struct tg_stats_cpu, service_bytes)),
+ .read_seq_string = tg_print_cpu_rwstat,
},
{
.name = "throttle.io_serviced",
.private = BLKCG_STAT_PRIV(BLKIO_POLICY_THROTL,
- offsetof(struct blkio_group_stats_cpu, serviced)),
- .read_seq_string = blkcg_print_cpu_rwstat,
+ offsetof(struct tg_stats_cpu, serviced)),
+ .read_seq_string = tg_print_cpu_rwstat,
},
{ } /* terminate */
};
@@ -1034,6 +1130,8 @@ static void throtl_shutdown_wq(struct request_queue *q)
static struct blkio_policy_type blkio_policy_throtl = {
.ops = {
.blkio_init_group_fn = throtl_init_blkio_group,
+ .blkio_exit_group_fn = throtl_exit_blkio_group,
+ .blkio_reset_group_stats_fn = throtl_reset_group_stats,
},
.plid = BLKIO_POLICY_THROTL,
.pdata_size = sizeof(struct throtl_grp),
--
1.7.7.3
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