diff options
Diffstat (limited to 'block/blk-throttle.c')
| -rw-r--r-- | block/blk-throttle.c | 128 |
1 files changed, 113 insertions, 15 deletions
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), |
