Ping...
Thanks,
Joseph
On 19/7/25 11:03, Joseph Qi wrote:
> Add blkio.throttle.io_service_time and blkio.throttle.io_wait_time to
> get per-cgroup io delay statistics in blk-throttle layer.
> io_service_time represents the time spent after io throttle to io
> completion, while io_wait_time represents the time spent on throttle
> queue.
>
> Signed-off-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
> ---
> block/bio.c | 4 ++
> block/blk-throttle.c | 130 +++++++++++++++++++++++++++++++++++++++++++++-
> include/linux/blk_types.h | 34 ++++++++++++
> 3 files changed, 167 insertions(+), 1 deletion(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index 299a0e7..3206462 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -1826,6 +1826,10 @@ void bio_endio(struct bio *bio)
> blk_throtl_bio_endio(bio);
> /* release cgroup info */
> bio_uninit(bio);
> +#ifdef CONFIG_BLK_DEV_THROTTLING
> + if (bio->bi_tg_end_io)
> + bio->bi_tg_end_io(bio);
> +#endif
> if (bio->bi_end_io)
> bio->bi_end_io(bio);
> }
> diff --git a/block/blk-throttle.c b/block/blk-throttle.c
> index 8ab6c81..a5880f0 100644
> --- a/block/blk-throttle.c
> +++ b/block/blk-throttle.c
> @@ -176,6 +176,11 @@ struct throtl_grp {
> unsigned int bio_cnt; /* total bios */
> unsigned int bad_bio_cnt; /* bios exceeding latency threshold */
> unsigned long bio_cnt_reset_time;
> +
> + /* total time spent on lower layer: scheduler, device and others */
> + struct blkg_rwstat service_time;
> + /* total time spent on block throttle */
> + struct blkg_rwstat wait_time;
> };
>
> /* We measure latency for request size from <= 4k to >= 1M */
> @@ -487,6 +492,10 @@ static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node)
> if (!tg)
> return NULL;
>
> + if (blkg_rwstat_init(&tg->service_time, gfp) ||
> + blkg_rwstat_init(&tg->wait_time, gfp))
> + goto err;
> +
> throtl_service_queue_init(&tg->service_queue);
>
> for (rw = READ; rw <= WRITE; rw++) {
> @@ -511,6 +520,12 @@ static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node)
> tg->idletime_threshold_conf = DFL_IDLE_THRESHOLD;
>
> return &tg->pd;
> +
> +err:
> + blkg_rwstat_exit(&tg->service_time);
> + blkg_rwstat_exit(&tg->wait_time);
> + kfree(tg);
> + return NULL;
> }
>
> static void throtl_pd_init(struct blkg_policy_data *pd)
> @@ -592,6 +607,8 @@ static void blk_throtl_update_limit_valid(struct throtl_data *td)
> static void throtl_pd_offline(struct blkg_policy_data *pd)
> {
> struct throtl_grp *tg = pd_to_tg(pd);
> + struct blkcg_gq *blkg = pd_to_blkg(pd);
> + struct blkcg_gq *parent = blkg->parent;
>
> tg->bps[READ][LIMIT_LOW] = 0;
> tg->bps[WRITE][LIMIT_LOW] = 0;
> @@ -602,6 +619,12 @@ static void throtl_pd_offline(struct blkg_policy_data *pd)
>
> if (!tg->td->limit_valid[tg->td->limit_index])
> throtl_upgrade_state(tg->td);
> + if (parent) {
> + blkg_rwstat_add_aux(&blkg_to_tg(parent)->service_time,
> + &tg->service_time);
> + blkg_rwstat_add_aux(&blkg_to_tg(parent)->wait_time,
> + &tg->wait_time);
> + }
> }
>
> static void throtl_pd_free(struct blkg_policy_data *pd)
> @@ -609,9 +632,19 @@ static void throtl_pd_free(struct blkg_policy_data *pd)
> struct throtl_grp *tg = pd_to_tg(pd);
>
> del_timer_sync(&tg->service_queue.pending_timer);
> + blkg_rwstat_exit(&tg->service_time);
> + blkg_rwstat_exit(&tg->wait_time);
> kfree(tg);
> }
>
> +static void throtl_pd_reset(struct blkg_policy_data *pd)
> +{
> + struct throtl_grp *tg = pd_to_tg(pd);
> +
> + blkg_rwstat_reset(&tg->service_time);
> + blkg_rwstat_reset(&tg->wait_time);
> +}
> +
> static struct throtl_grp *
> throtl_rb_first(struct throtl_service_queue *parent_sq)
> {
> @@ -1019,6 +1052,64 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
> return false;
> }
>
> +static void throtl_stats_update_completion(struct throtl_grp *tg,
> + uint64_t start_time,
> + uint64_t io_start_time,
> + int op)
> +{
> + unsigned long flags;
> + uint64_t now = sched_clock();
> +
> + local_irq_save(flags);
> + if (time_after64(now, io_start_time))
> + blkg_rwstat_add(&tg->service_time, op, now - io_start_time);
> + if (time_after64(io_start_time, start_time))
> + blkg_rwstat_add(&tg->wait_time, op, io_start_time - start_time);
> + local_irq_restore(flags);
> +}
> +
> +static void throtl_bio_end_io(struct bio *bio)
> +{
> + struct throtl_grp *tg;
> +
> + rcu_read_lock();
> + /* see comments in throtl_bio_stats_start() */
> + if (bio_flagged(bio, BIO_THROTL_STATED))
> + goto out;
> +
> + tg = (struct throtl_grp *)bio->bi_tg_private;
> + if (!tg)
> + goto out;
> +
> + throtl_stats_update_completion(tg, bio_start_time_ns(bio),
> + bio_io_start_time_ns(bio),
> + bio_op(bio));
> + blkg_put(tg_to_blkg(tg));
> + bio_clear_flag(bio, BIO_THROTL_STATED);
> +out:
> + rcu_read_unlock();
> +}
> +
> +static inline void throtl_bio_stats_start(struct bio *bio, struct throtl_grp *tg)
> +{
> + int op = bio_op(bio);
> +
> + /*
> + * It may happen that end_io will be called twice like dm-thin,
> + * which will save origin end_io first, and call its overwrite
> + * end_io and then the saved end_io. We use bio flag
> + * BIO_THROTL_STATED to do only once statistics.
> + */
> + if ((op == REQ_OP_READ || op == REQ_OP_WRITE) &&
> + !bio_flagged(bio, BIO_THROTL_STATED)) {
> + blkg_get(tg_to_blkg(tg));
> + bio_set_flag(bio, BIO_THROTL_STATED);
> + bio->bi_tg_end_io = throtl_bio_end_io;
> + bio->bi_tg_private = tg;
> + bio_set_start_time_ns(bio);
> + }
> +}
> +
> static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
> {
> bool rw = bio_data_dir(bio);
> @@ -1462,6 +1553,25 @@ static ssize_t tg_set_conf_uint(struct kernfs_open_file *of,
> return tg_set_conf(of, buf, nbytes, off, false);
> }
>
> +static u64 tg_prfill_rwstat_field(struct seq_file *sf,
> + struct blkg_policy_data *pd,
> + int off)
> +{
> + struct throtl_grp *tg = pd_to_tg(pd);
> + struct blkg_rwstat_sample rwstat = { };
> +
> + blkg_rwstat_read((void *)tg + off, &rwstat);
> + return __blkg_prfill_rwstat(sf, pd, &rwstat);
> +}
> +
> +static int tg_print_rwstat(struct seq_file *sf, void *v)
> +{
> + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
> + tg_prfill_rwstat_field, &blkcg_policy_throtl,
> + seq_cft(sf)->private, true);
> + return 0;
> +}
> +
> static struct cftype throtl_legacy_files[] = {
> {
> .name = "throttle.read_bps_device",
> @@ -1507,6 +1617,16 @@ static ssize_t tg_set_conf_uint(struct kernfs_open_file *of,
> .private = (unsigned long)&blkcg_policy_throtl,
> .seq_show = blkg_print_stat_ios_recursive,
> },
> + {
> + .name = "throttle.io_service_time",
> + .private = offsetof(struct throtl_grp, service_time),
> + .seq_show = tg_print_rwstat,
> + },
> + {
> + .name = "throttle.io_wait_time",
> + .private = offsetof(struct throtl_grp, wait_time),
> + .seq_show = tg_print_rwstat,
> + },
> { } /* terminate */
> };
>
> @@ -1732,6 +1852,7 @@ static void throtl_shutdown_wq(struct request_queue *q)
> .pd_online_fn = throtl_pd_online,
> .pd_offline_fn = throtl_pd_offline,
> .pd_free_fn = throtl_pd_free,
> + .pd_reset_stats_fn = throtl_pd_reset,
> };
>
> static unsigned long __tg_last_low_overflow_time(struct throtl_grp *tg)
> @@ -2125,7 +2246,12 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
> WARN_ON_ONCE(!rcu_read_lock_held());
>
> /* see throtl_charge_bio() */
> - if (bio_flagged(bio, BIO_THROTTLED) || !tg->has_rules[rw])
> + if (bio_flagged(bio, BIO_THROTTLED))
> + goto out;
> +
> + throtl_bio_stats_start(bio, tg);
> +
> + if (!tg->has_rules[rw])
> goto out;
>
> spin_lock_irq(&q->queue_lock);
> @@ -2212,6 +2338,8 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
> out_unlock:
> spin_unlock_irq(&q->queue_lock);
> out:
> + if (!throttled)
> + bio_set_io_start_time_ns(bio);
> bio_set_flag(bio, BIO_THROTTLED);
>
> #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index feff3fe..6906bc6 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -9,6 +9,7 @@
> #include <linux/types.h>
> #include <linux/bvec.h>
> #include <linux/ktime.h>
> +#include <linux/sched/clock.h>
>
> struct bio_set;
> struct bio;
> @@ -169,6 +170,12 @@ struct bio {
> */
> struct blkcg_gq *bi_blkg;
> struct bio_issue bi_issue;
> +#ifdef CONFIG_BLK_DEV_THROTTLING
> + unsigned long long start_time_ns; /* when passed to block throttle */
> + unsigned long long io_start_time_ns; /* when no more throttle */
> + bio_end_io_t *bi_tg_end_io;
> + void *bi_tg_private;
> +#endif
> #endif
> union {
> #if defined(CONFIG_BLK_DEV_INTEGRITY)
> @@ -218,6 +225,7 @@ enum {
> * of this bio. */
> BIO_QUEUE_ENTERED, /* can use blk_queue_enter_live() */
> BIO_TRACKED, /* set if bio goes through the rq_qos path */
> + BIO_THROTL_STATED, /* bio already stated */
> BIO_FLAG_LAST
> };
>
> @@ -248,6 +256,32 @@ enum {
> */
> #define BIO_RESET_BITS BVEC_POOL_OFFSET
>
> +#ifdef CONFIG_BLK_DEV_THROTTLING
> +static inline void bio_set_start_time_ns(struct bio *bio)
> +{
> + preempt_disable();
> + bio->start_time_ns = sched_clock();
> + preempt_enable();
> +}
> +
> +static inline void bio_set_io_start_time_ns(struct bio *bio)
> +{
> + preempt_disable();
> + bio->io_start_time_ns = sched_clock();
> + preempt_enable();
> +}
> +
> +static inline uint64_t bio_start_time_ns(struct bio *bio)
> +{
> + return bio->start_time_ns;
> +}
> +
> +static inline uint64_t bio_io_start_time_ns(struct bio *bio)
> +{
> + return bio->io_start_time_ns;
> +}
> +#endif
> +
> typedef __u32 __bitwise blk_mq_req_flags_t;
>
> /*
>
