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blkcg: move blkio_group_stats_cpu and friends to blk-throttle.c
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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@kernel.org>
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Tejun Heo committed Apr 1, 2012
1 parent 155fead commit 8a3d261
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Showing 3 changed files with 114 additions and 125 deletions.
98 changes: 1 addition & 97 deletions block/blk-cgroup.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);

Expand All @@ -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
Expand All @@ -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);
}

Expand All @@ -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));
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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.
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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)
{
Expand All @@ -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);
Expand Down
13 changes: 0 additions & 13 deletions block/blk-cgroup.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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];
Expand All @@ -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));
};
Expand All @@ -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;
};

Expand Down
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