diff options
| -rw-r--r-- | block/blk-iolatency.c | 179 |
1 files changed, 145 insertions, 34 deletions
diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index e7be77b0ce8b..fd246805b0be 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -115,9 +115,21 @@ struct child_latency_info { atomic_t scale_cookie; }; +struct percentile_stats { + u64 total; + u64 missed; +}; + +struct latency_stat { + union { + struct percentile_stats ps; + struct blk_rq_stat rqs; + }; +}; + struct iolatency_grp { struct blkg_policy_data pd; - struct blk_rq_stat __percpu *stats; + struct latency_stat __percpu *stats; struct blk_iolatency *blkiolat; struct rq_depth rq_depth; struct rq_wait rq_wait; @@ -132,6 +144,7 @@ struct iolatency_grp { /* Our current number of IO's for the last summation. */ u64 nr_samples; + bool ssd; struct child_latency_info child_lat; }; @@ -172,6 +185,80 @@ static inline struct blkcg_gq *lat_to_blkg(struct iolatency_grp *iolat) return pd_to_blkg(&iolat->pd); } +static inline void latency_stat_init(struct iolatency_grp *iolat, + struct latency_stat *stat) +{ + if (iolat->ssd) { + stat->ps.total = 0; + stat->ps.missed = 0; + } else + blk_rq_stat_init(&stat->rqs); +} + +static inline void latency_stat_sum(struct iolatency_grp *iolat, + struct latency_stat *sum, + struct latency_stat *stat) +{ + if (iolat->ssd) { + sum->ps.total += stat->ps.total; + sum->ps.missed += stat->ps.missed; + } else + blk_rq_stat_sum(&sum->rqs, &stat->rqs); +} + +static inline void latency_stat_record_time(struct iolatency_grp *iolat, + u64 req_time) +{ + struct latency_stat *stat = get_cpu_ptr(iolat->stats); + if (iolat->ssd) { + if (req_time >= iolat->min_lat_nsec) + stat->ps.missed++; + stat->ps.total++; + } else + blk_rq_stat_add(&stat->rqs, req_time); + put_cpu_ptr(stat); +} + +static inline bool latency_sum_ok(struct iolatency_grp *iolat, + struct latency_stat *stat) +{ + if (iolat->ssd) { + u64 thresh = div64_u64(stat->ps.total, 10); + thresh = max(thresh, 1ULL); + return stat->ps.missed < thresh; + } + return stat->rqs.mean <= iolat->min_lat_nsec; +} + +static inline u64 latency_stat_samples(struct iolatency_grp *iolat, + struct latency_stat *stat) +{ + if (iolat->ssd) + return stat->ps.total; + return stat->rqs.nr_samples; +} + +static inline void iolat_update_total_lat_avg(struct iolatency_grp *iolat, + struct latency_stat *stat) +{ + int exp_idx; + + if (iolat->ssd) + return; + + /* + * CALC_LOAD takes in a number stored in fixed point representation. + * Because we are using this for IO time in ns, the values stored + * are significantly larger than the FIXED_1 denominator (2048). + * Therefore, rounding errors in the calculation are negligible and + * can be ignored. + */ + exp_idx = min_t(int, BLKIOLATENCY_NR_EXP_FACTORS - 1, + div64_u64(iolat->cur_win_nsec, + BLKIOLATENCY_EXP_BUCKET_SIZE)); + CALC_LOAD(iolat->lat_avg, iolatency_exp_factors[exp_idx], stat->rqs.mean); +} + static inline bool iolatency_may_queue(struct iolatency_grp *iolat, wait_queue_entry_t *wait, bool first_block) @@ -418,7 +505,6 @@ static void iolatency_record_time(struct iolatency_grp *iolat, struct bio_issue *issue, u64 now, bool issue_as_root) { - struct blk_rq_stat *rq_stat; u64 start = bio_issue_time(issue); u64 req_time; @@ -444,9 +530,7 @@ static void iolatency_record_time(struct iolatency_grp *iolat, return; } - rq_stat = get_cpu_ptr(iolat->stats); - blk_rq_stat_add(rq_stat, req_time); - put_cpu_ptr(rq_stat); + latency_stat_record_time(iolat, req_time); } #define BLKIOLATENCY_MIN_ADJUST_TIME (500 * NSEC_PER_MSEC) @@ -457,17 +541,17 @@ static void iolatency_check_latencies(struct iolatency_grp *iolat, u64 now) struct blkcg_gq *blkg = lat_to_blkg(iolat); struct iolatency_grp *parent; struct child_latency_info *lat_info; - struct blk_rq_stat stat; + struct latency_stat stat; unsigned long flags; - int cpu, exp_idx; + int cpu; - blk_rq_stat_init(&stat); + latency_stat_init(iolat, &stat); preempt_disable(); for_each_online_cpu(cpu) { - struct blk_rq_stat *s; + struct latency_stat *s; s = per_cpu_ptr(iolat->stats, cpu); - blk_rq_stat_sum(&stat, s); - blk_rq_stat_init(s); + latency_stat_sum(iolat, &stat, s); + latency_stat_init(iolat, s); } preempt_enable(); @@ -477,41 +561,33 @@ static void iolatency_check_latencies(struct iolatency_grp *iolat, u64 now) lat_info = &parent->child_lat; - /* - * CALC_LOAD takes in a number stored in fixed point representation. - * Because we are using this for IO time in ns, the values stored - * are significantly larger than the FIXED_1 denominator (2048). - * Therefore, rounding errors in the calculation are negligible and - * can be ignored. - */ - exp_idx = min_t(int, BLKIOLATENCY_NR_EXP_FACTORS - 1, - div64_u64(iolat->cur_win_nsec, - BLKIOLATENCY_EXP_BUCKET_SIZE)); - CALC_LOAD(iolat->lat_avg, iolatency_exp_factors[exp_idx], stat.mean); + iolat_update_total_lat_avg(iolat, &stat); /* Everything is ok and we don't need to adjust the scale. */ - if (stat.mean <= iolat->min_lat_nsec && + if (latency_sum_ok(iolat, &stat) && atomic_read(&lat_info->scale_cookie) == DEFAULT_SCALE_COOKIE) return; /* Somebody beat us to the punch, just bail. */ spin_lock_irqsave(&lat_info->lock, flags); lat_info->nr_samples -= iolat->nr_samples; - lat_info->nr_samples += stat.nr_samples; - iolat->nr_samples = stat.nr_samples; + lat_info->nr_samples += latency_stat_samples(iolat, &stat); + iolat->nr_samples = latency_stat_samples(iolat, &stat); if ((lat_info->last_scale_event >= now || now - lat_info->last_scale_event < BLKIOLATENCY_MIN_ADJUST_TIME) && lat_info->scale_lat <= iolat->min_lat_nsec) goto out; - if (stat.mean <= iolat->min_lat_nsec && - stat.nr_samples >= BLKIOLATENCY_MIN_GOOD_SAMPLES) { + if (latency_sum_ok(iolat, &stat)) { + if (latency_stat_samples(iolat, &stat) < + BLKIOLATENCY_MIN_GOOD_SAMPLES) + goto out; if (lat_info->scale_grp == iolat) { lat_info->last_scale_event = now; scale_cookie_change(iolat->blkiolat, lat_info, true); } - } else if (stat.mean > iolat->min_lat_nsec) { + } else { lat_info->last_scale_event = now; if (!lat_info->scale_grp || lat_info->scale_lat > iolat->min_lat_nsec) { @@ -808,13 +884,43 @@ static int iolatency_print_limit(struct seq_file *sf, void *v) return 0; } +static size_t iolatency_ssd_stat(struct iolatency_grp *iolat, char *buf, + size_t size) +{ + struct latency_stat stat; + int cpu; + + latency_stat_init(iolat, &stat); + preempt_disable(); + for_each_online_cpu(cpu) { + struct latency_stat *s; + s = per_cpu_ptr(iolat->stats, cpu); + latency_stat_sum(iolat, &stat, s); + } + preempt_enable(); + + if (iolat->rq_depth.max_depth == UINT_MAX) + return scnprintf(buf, size, " missed=%llu total=%llu depth=max", + (unsigned long long)stat.ps.missed, + (unsigned long long)stat.ps.total); + return scnprintf(buf, size, " missed=%llu total=%llu depth=%u", + (unsigned long long)stat.ps.missed, + (unsigned long long)stat.ps.total, + iolat->rq_depth.max_depth); +} + static size_t iolatency_pd_stat(struct blkg_policy_data *pd, char *buf, size_t size) { struct iolatency_grp *iolat = pd_to_lat(pd); - unsigned long long avg_lat = div64_u64(iolat->lat_avg, NSEC_PER_USEC); - unsigned long long cur_win = div64_u64(iolat->cur_win_nsec, NSEC_PER_MSEC); + unsigned long long avg_lat; + unsigned long long cur_win; + + if (iolat->ssd) + return iolatency_ssd_stat(iolat, buf, size); + avg_lat = div64_u64(iolat->lat_avg, NSEC_PER_USEC); + cur_win = div64_u64(iolat->cur_win_nsec, NSEC_PER_MSEC); if (iolat->rq_depth.max_depth == UINT_MAX) return scnprintf(buf, size, " depth=max avg_lat=%llu win=%llu", avg_lat, cur_win); @@ -831,8 +937,8 @@ static struct blkg_policy_data *iolatency_pd_alloc(gfp_t gfp, int node) iolat = kzalloc_node(sizeof(*iolat), gfp, node); if (!iolat) return NULL; - iolat->stats = __alloc_percpu_gfp(sizeof(struct blk_rq_stat), - __alignof__(struct blk_rq_stat), gfp); + iolat->stats = __alloc_percpu_gfp(sizeof(struct latency_stat), + __alignof__(struct latency_stat), gfp); if (!iolat->stats) { kfree(iolat); return NULL; @@ -849,10 +955,15 @@ static void iolatency_pd_init(struct blkg_policy_data *pd) u64 now = ktime_to_ns(ktime_get()); int cpu; + if (blk_queue_nonrot(blkg->q)) + iolat->ssd = true; + else + iolat->ssd = false; + for_each_possible_cpu(cpu) { - struct blk_rq_stat *stat; + struct latency_stat *stat; stat = per_cpu_ptr(iolat->stats, cpu); - blk_rq_stat_init(stat); + latency_stat_init(iolat, stat); } rq_wait_init(&iolat->rq_wait); |