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72e06c2551
linux/block/blk-cgroup.h
Tejun Heo 72e06c2551 blkcg: shoot down blkio_groups on elevator switch 
Elevator switch may involve changes to blkcg policies.  Implement
shoot down of blkio_groups.

Combined with the previous bypass updates, the end goal is updating
blkcg core such that it can ensure that blkcg's being affected become
quiescent and don't have any per-blkg data hanging around before
commencing any policy updates.  Until queues are made aware of the
policies that applies to them, as an interim step, all per-policy blkg
data will be shot down.

* blk-throtl doesn't need this change as it can't be disabled for a
  live queue; however, update it anyway as the scheduled blkg
  unification requires this behavior change.  This means that
  blk-throtl configuration will be unnecessarily lost over elevator
  switch.  This oddity will be removed after blkcg learns to associate
  individual policies with request_queues.

* blk-throtl dosen't shoot down root_tg.  This is to ease transition.
  Unified blkg will always have persistent root group and not shooting
  down root_tg for now eases transition to that point by avoiding
  having to update td->root_tg and is safe as blk-throtl can never be
  disabled

-v2: Vivek pointed out that group list is not guaranteed to be empty
     on return from clear function if it raced cgroup removal and
     lost.  Fix it by waiting a bit and retrying.  This kludge will
     soon be removed once locking is updated such that blkg is never
     in limbo state between blkcg and request_queue locks.

     blk-throtl no longer shoots down root_tg to avoid breaking
     td->root_tg.

     Also, Nest queue_lock inside blkio_list_lock not the other way
     around to avoid introduce possible deadlock via blkcg lock.

-v3: blkcg_clear_queue() repositioned and renamed to
     blkg_destroy_all() to increase consistency with later changes.
     cfq_clear_queue() updated to check q->elevator before
     dereferencing it to avoid NULL dereference on not fully
     initialized queues (used by later change).

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:22 +01:00

362 lines
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C
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#ifndef _BLK_CGROUP_H
#define _BLK_CGROUP_H
/*
* Common Block IO controller cgroup interface
*
* Based on ideas and code from CFQ, CFS and BFQ:
* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
*
* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
* Paolo Valente <paolo.valente@unimore.it>
*
* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
* Nauman Rafique <nauman@google.com>
*/
#include <linux/cgroup.h>
#include <linux/u64_stats_sync.h>
enum blkio_policy_id {
BLKIO_POLICY_PROP = 0, /* Proportional Bandwidth division */
BLKIO_POLICY_THROTL, /* Throttling */
};
/* Max limits for throttle policy */
#define THROTL_IOPS_MAX UINT_MAX
#ifdef CONFIG_BLK_CGROUP
enum stat_type {
/* Total time spent (in ns) between request dispatch to the driver and
* request completion for IOs doen by this cgroup. This may not be
* accurate when NCQ is turned on. */
BLKIO_STAT_SERVICE_TIME = 0,
/* Total time spent waiting in scheduler queue in ns */
BLKIO_STAT_WAIT_TIME,
/* Number of IOs queued up */
BLKIO_STAT_QUEUED,
/* All the single valued stats go below this */
BLKIO_STAT_TIME,
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* Time not charged to this cgroup */
BLKIO_STAT_UNACCOUNTED_TIME,
BLKIO_STAT_AVG_QUEUE_SIZE,
BLKIO_STAT_IDLE_TIME,
BLKIO_STAT_EMPTY_TIME,
BLKIO_STAT_GROUP_WAIT_TIME,
BLKIO_STAT_DEQUEUE
#endif
};
/* Per cpu stats */
enum stat_type_cpu {
BLKIO_STAT_CPU_SECTORS,
/* Total bytes transferred */
BLKIO_STAT_CPU_SERVICE_BYTES,
/* Total IOs serviced, post merge */
BLKIO_STAT_CPU_SERVICED,
/* Number of IOs merged */
BLKIO_STAT_CPU_MERGED,
BLKIO_STAT_CPU_NR
};
enum stat_sub_type {
BLKIO_STAT_READ = 0,
BLKIO_STAT_WRITE,
BLKIO_STAT_SYNC,
BLKIO_STAT_ASYNC,
BLKIO_STAT_TOTAL
};
/* blkg state flags */
enum blkg_state_flags {
BLKG_waiting = 0,
BLKG_idling,
BLKG_empty,
};
/* cgroup files owned by proportional weight policy */
enum blkcg_file_name_prop {
BLKIO_PROP_weight = 1,
BLKIO_PROP_weight_device,
BLKIO_PROP_io_service_bytes,
BLKIO_PROP_io_serviced,
BLKIO_PROP_time,
BLKIO_PROP_sectors,
BLKIO_PROP_unaccounted_time,
BLKIO_PROP_io_service_time,
BLKIO_PROP_io_wait_time,
BLKIO_PROP_io_merged,
BLKIO_PROP_io_queued,
BLKIO_PROP_avg_queue_size,
BLKIO_PROP_group_wait_time,
BLKIO_PROP_idle_time,
BLKIO_PROP_empty_time,
BLKIO_PROP_dequeue,
};
/* cgroup files owned by throttle policy */
enum blkcg_file_name_throtl {
BLKIO_THROTL_read_bps_device,
BLKIO_THROTL_write_bps_device,
BLKIO_THROTL_read_iops_device,
BLKIO_THROTL_write_iops_device,
BLKIO_THROTL_io_service_bytes,
BLKIO_THROTL_io_serviced,
};
struct blkio_cgroup {
struct cgroup_subsys_state css;
unsigned int weight;
spinlock_t lock;
struct hlist_head blkg_list;
struct list_head policy_list; /* list of blkio_policy_node */
};
struct blkio_group_stats {
/* total disk time and nr sectors dispatched by this group */
uint64_t time;
uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL];
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* Time not charged to this cgroup */
uint64_t unaccounted_time;
/* Sum of number of IOs queued across all samples */
uint64_t avg_queue_size_sum;
/* Count of samples taken for average */
uint64_t avg_queue_size_samples;
/* How many times this group has been removed from service tree */
unsigned long dequeue;
/* Total time spent waiting for it to be assigned a timeslice. */
uint64_t group_wait_time;
uint64_t start_group_wait_time;
/* Time spent idling for this blkio_group */
uint64_t idle_time;
uint64_t start_idle_time;
/*
* Total time when we have requests queued and do not contain the
* current active queue.
*/
uint64_t empty_time;
uint64_t start_empty_time;
uint16_t flags;
#endif
};
/* Per cpu blkio group stats */
struct blkio_group_stats_cpu {
uint64_t sectors;
uint64_t stat_arr_cpu[BLKIO_STAT_CPU_NR][BLKIO_STAT_TOTAL];
struct u64_stats_sync syncp;
};
struct blkio_group {
/* An rcu protected unique identifier for the group */
void *key;
struct hlist_node blkcg_node;
unsigned short blkcg_id;
/* Store cgroup path */
char path[128];
/* The device MKDEV(major, minor), this group has been created for */
dev_t dev;
/* policy which owns this blk group */
enum blkio_policy_id plid;
/* Need to serialize the stats in the case of reset/update */
spinlock_t stats_lock;
struct blkio_group_stats stats;
/* Per cpu stats pointer */
struct blkio_group_stats_cpu __percpu *stats_cpu;
};
struct blkio_policy_node {
struct list_head node;
dev_t dev;
/* This node belongs to max bw policy or porportional weight policy */
enum blkio_policy_id plid;
/* cgroup file to which this rule belongs to */
int fileid;
union {
unsigned int weight;
/*
* Rate read/write in terms of bytes per second
* Whether this rate represents read or write is determined
* by file type "fileid".
*/
u64 bps;
unsigned int iops;
} val;
};
extern unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
dev_t dev);
extern uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg,
dev_t dev);
extern uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg,
dev_t dev);
extern unsigned int blkcg_get_read_iops(struct blkio_cgroup *blkcg,
dev_t dev);
extern unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg,
dev_t dev);
typedef void (blkio_unlink_group_fn) (void *key, struct blkio_group *blkg);
typedef bool (blkio_clear_queue_fn)(struct request_queue *q);
typedef void (blkio_update_group_weight_fn) (void *key,
struct blkio_group *blkg, unsigned int weight);
typedef void (blkio_update_group_read_bps_fn) (void * key,
struct blkio_group *blkg, u64 read_bps);
typedef void (blkio_update_group_write_bps_fn) (void *key,
struct blkio_group *blkg, u64 write_bps);
typedef void (blkio_update_group_read_iops_fn) (void *key,
struct blkio_group *blkg, unsigned int read_iops);
typedef void (blkio_update_group_write_iops_fn) (void *key,
struct blkio_group *blkg, unsigned int write_iops);
struct blkio_policy_ops {
blkio_unlink_group_fn *blkio_unlink_group_fn;
blkio_clear_queue_fn *blkio_clear_queue_fn;
blkio_update_group_weight_fn *blkio_update_group_weight_fn;
blkio_update_group_read_bps_fn *blkio_update_group_read_bps_fn;
blkio_update_group_write_bps_fn *blkio_update_group_write_bps_fn;
blkio_update_group_read_iops_fn *blkio_update_group_read_iops_fn;
blkio_update_group_write_iops_fn *blkio_update_group_write_iops_fn;
};
struct blkio_policy_type {
struct list_head list;
struct blkio_policy_ops ops;
enum blkio_policy_id plid;
};
/* Blkio controller policy registration */
extern void blkio_policy_register(struct blkio_policy_type *);
extern void blkio_policy_unregister(struct blkio_policy_type *);
extern void blkg_destroy_all(struct request_queue *q);
static inline char *blkg_path(struct blkio_group *blkg)
{
return blkg->path;
}
#else
struct blkio_group {
};
struct blkio_policy_type {
};
static inline void blkio_policy_register(struct blkio_policy_type *blkiop) { }
static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
static inline void blkg_destroy_all(struct request_queue *q) { }
static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
#endif
#define BLKIO_WEIGHT_MIN 10
#define BLKIO_WEIGHT_MAX 1000
#define BLKIO_WEIGHT_DEFAULT 500
#ifdef CONFIG_DEBUG_BLK_CGROUP
void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg);
void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
unsigned long dequeue);
void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg);
void blkiocg_update_idle_time_stats(struct blkio_group *blkg);
void blkiocg_set_start_empty_time(struct blkio_group *blkg);
#define BLKG_FLAG_FNS(name) \
static inline void blkio_mark_blkg_##name( \
struct blkio_group_stats *stats) \
{ \
stats->flags |= (1 << BLKG_##name); \
} \
static inline void blkio_clear_blkg_##name( \
struct blkio_group_stats *stats) \
{ \
stats->flags &= ~(1 << BLKG_##name); \
} \
static inline int blkio_blkg_##name(struct blkio_group_stats *stats) \
{ \
return (stats->flags & (1 << BLKG_##name)) != 0; \
} \
BLKG_FLAG_FNS(waiting)
BLKG_FLAG_FNS(idling)
BLKG_FLAG_FNS(empty)
#undef BLKG_FLAG_FNS
#else
static inline void blkiocg_update_avg_queue_size_stats(
struct blkio_group *blkg) {}
static inline void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
unsigned long dequeue) {}
static inline void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
{}
static inline void blkiocg_update_idle_time_stats(struct blkio_group *blkg) {}
static inline void blkiocg_set_start_empty_time(struct blkio_group *blkg) {}
#endif
#ifdef CONFIG_BLK_CGROUP
extern struct blkio_cgroup blkio_root_cgroup;
extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
extern struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk);
extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
struct blkio_group *blkg, void *key, dev_t dev,
enum blkio_policy_id plid);
extern int blkio_alloc_blkg_stats(struct blkio_group *blkg);
extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
void *key);
void blkiocg_update_timeslice_used(struct blkio_group *blkg,
unsigned long time,
unsigned long unaccounted_time);
void blkiocg_update_dispatch_stats(struct blkio_group *blkg, uint64_t bytes,
bool direction, bool sync);
void blkiocg_update_completion_stats(struct blkio_group *blkg,
uint64_t start_time, uint64_t io_start_time, bool direction, bool sync);
void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
bool sync);
void blkiocg_update_io_add_stats(struct blkio_group *blkg,
struct blkio_group *curr_blkg, bool direction, bool sync);
void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
bool direction, bool sync);
#else
struct cgroup;
static inline struct blkio_cgroup *
cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
static inline struct blkio_cgroup *
task_blkio_cgroup(struct task_struct *tsk) { return NULL; }
static inline void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
struct blkio_group *blkg, void *key, dev_t dev,
enum blkio_policy_id plid) {}
static inline int blkio_alloc_blkg_stats(struct blkio_group *blkg) { return 0; }
static inline int
blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }
static inline struct blkio_group *
blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }
static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg,
unsigned long time,
unsigned long unaccounted_time)
{}
static inline void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
uint64_t bytes, bool direction, bool sync) {}
static inline void blkiocg_update_completion_stats(struct blkio_group *blkg,
uint64_t start_time, uint64_t io_start_time, bool direction,
bool sync) {}
static inline void blkiocg_update_io_merged_stats(struct blkio_group *blkg,
bool direction, bool sync) {}
static inline void blkiocg_update_io_add_stats(struct blkio_group *blkg,
struct blkio_group *curr_blkg, bool direction, bool sync) {}
static inline void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
bool direction, bool sync) {}
#endif
#endif /* _BLK_CGROUP_H */
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