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-rw-r--r--block/blk-iolatency.c179
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);