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-rw-r--r--block/blk-iocost.c86
1 files changed, 65 insertions, 21 deletions
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 7c1fe605d0d6..8ac4aad66ebc 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -260,6 +260,7 @@ enum {
VTIME_PER_SEC_SHIFT = 37,
VTIME_PER_SEC = 1LLU << VTIME_PER_SEC_SHIFT,
VTIME_PER_USEC = VTIME_PER_SEC / USEC_PER_SEC,
+ VTIME_PER_NSEC = VTIME_PER_SEC / NSEC_PER_SEC,
/* bound vrate adjustments within two orders of magnitude */
VRATE_MIN_PPM = 10000, /* 1% */
@@ -1206,14 +1207,14 @@ static enum hrtimer_restart iocg_waitq_timer_fn(struct hrtimer *timer)
return HRTIMER_NORESTART;
}
-static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now, u64 cost)
+static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now)
{
struct ioc *ioc = iocg->ioc;
struct blkcg_gq *blkg = iocg_to_blkg(iocg);
u64 vtime = atomic64_read(&iocg->vtime);
u64 vmargin = ioc->margin_us * now->vrate;
u64 margin_ns = ioc->margin_us * NSEC_PER_USEC;
- u64 expires, oexpires;
+ u64 delta_ns, expires, oexpires;
u32 hw_inuse;
lockdep_assert_held(&iocg->waitq.lock);
@@ -1236,15 +1237,10 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now, u64 cost)
return false;
/* use delay */
- if (cost) {
- u64 cost_ns = DIV64_U64_ROUND_UP(cost * NSEC_PER_USEC,
- now->vrate);
- blkcg_add_delay(blkg, now->now_ns, cost_ns);
- }
- blkcg_use_delay(blkg);
-
- expires = now->now_ns + DIV64_U64_ROUND_UP(vtime - now->vnow,
- now->vrate) * NSEC_PER_USEC;
+ delta_ns = DIV64_U64_ROUND_UP(vtime - now->vnow,
+ now->vrate) * NSEC_PER_USEC;
+ blkcg_set_delay(blkg, delta_ns);
+ expires = now->now_ns + delta_ns;
/* if already active and close enough, don't bother */
oexpires = ktime_to_ns(hrtimer_get_softexpires(&iocg->delay_timer));
@@ -1265,7 +1261,7 @@ static enum hrtimer_restart iocg_delay_timer_fn(struct hrtimer *timer)
spin_lock_irqsave(&iocg->waitq.lock, flags);
ioc_now(iocg->ioc, &now);
- iocg_kick_delay(iocg, &now, 0);
+ iocg_kick_delay(iocg, &now);
spin_unlock_irqrestore(&iocg->waitq.lock, flags);
return HRTIMER_NORESTART;
@@ -1383,7 +1379,7 @@ static void ioc_timer_fn(struct timer_list *timer)
if (waitqueue_active(&iocg->waitq) || iocg->abs_vdebt) {
/* might be oversleeping vtime / hweight changes, kick */
iocg_kick_waitq(iocg, &now);
- iocg_kick_delay(iocg, &now, 0);
+ iocg_kick_delay(iocg, &now);
} else if (iocg_is_idle(iocg)) {
/* no waiter and idle, deactivate */
iocg->last_inuse = iocg->inuse;
@@ -1543,19 +1539,39 @@ skip_surplus_transfers:
if (rq_wait_pct > RQ_WAIT_BUSY_PCT ||
missed_ppm[READ] > ppm_rthr ||
missed_ppm[WRITE] > ppm_wthr) {
+ /* clearly missing QoS targets, slow down vrate */
ioc->busy_level = max(ioc->busy_level, 0);
ioc->busy_level++;
} else if (rq_wait_pct <= RQ_WAIT_BUSY_PCT * UNBUSY_THR_PCT / 100 &&
missed_ppm[READ] <= ppm_rthr * UNBUSY_THR_PCT / 100 &&
missed_ppm[WRITE] <= ppm_wthr * UNBUSY_THR_PCT / 100) {
- /* take action iff there is contention */
- if (nr_shortages && !nr_lagging) {
+ /* QoS targets are being met with >25% margin */
+ if (nr_shortages) {
+ /*
+ * We're throttling while the device has spare
+ * capacity. If vrate was being slowed down, stop.
+ */
ioc->busy_level = min(ioc->busy_level, 0);
- /* redistribute surpluses first */
- if (!nr_surpluses)
+
+ /*
+ * If there are IOs spanning multiple periods, wait
+ * them out before pushing the device harder. If
+ * there are surpluses, let redistribution work it
+ * out first.
+ */
+ if (!nr_lagging && !nr_surpluses)
ioc->busy_level--;
+ } else {
+ /*
+ * Nobody is being throttled and the users aren't
+ * issuing enough IOs to saturate the device. We
+ * simply don't know how close the device is to
+ * saturation. Coast.
+ */
+ ioc->busy_level = 0;
}
} else {
+ /* inside the hysterisis margin, we're good */
ioc->busy_level = 0;
}
@@ -1678,6 +1694,31 @@ static u64 calc_vtime_cost(struct bio *bio, struct ioc_gq *iocg, bool is_merge)
return cost;
}
+static void calc_size_vtime_cost_builtin(struct request *rq, struct ioc *ioc,
+ u64 *costp)
+{
+ unsigned int pages = blk_rq_stats_sectors(rq) >> IOC_SECT_TO_PAGE_SHIFT;
+
+ switch (req_op(rq)) {
+ case REQ_OP_READ:
+ *costp = pages * ioc->params.lcoefs[LCOEF_RPAGE];
+ break;
+ case REQ_OP_WRITE:
+ *costp = pages * ioc->params.lcoefs[LCOEF_WPAGE];
+ break;
+ default:
+ *costp = 0;
+ }
+}
+
+static u64 calc_size_vtime_cost(struct request *rq, struct ioc *ioc)
+{
+ u64 cost;
+
+ calc_size_vtime_cost_builtin(rq, ioc, &cost);
+ return cost;
+}
+
static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio)
{
struct blkcg_gq *blkg = bio->bi_blkg;
@@ -1762,7 +1803,7 @@ static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio)
*/
if (bio_issue_as_root_blkg(bio) || fatal_signal_pending(current)) {
iocg->abs_vdebt += abs_cost;
- if (iocg_kick_delay(iocg, &now, cost))
+ if (iocg_kick_delay(iocg, &now))
blkcg_schedule_throttle(rqos->q,
(bio->bi_opf & REQ_SWAP) == REQ_SWAP);
spin_unlock_irq(&iocg->waitq.lock);
@@ -1850,7 +1891,7 @@ static void ioc_rqos_merge(struct rq_qos *rqos, struct request *rq,
spin_lock_irqsave(&iocg->waitq.lock, flags);
if (likely(!list_empty(&iocg->active_list))) {
iocg->abs_vdebt += abs_cost;
- iocg_kick_delay(iocg, &now, cost);
+ iocg_kick_delay(iocg, &now);
} else {
iocg_commit_bio(iocg, bio, cost);
}
@@ -1868,7 +1909,7 @@ static void ioc_rqos_done_bio(struct rq_qos *rqos, struct bio *bio)
static void ioc_rqos_done(struct rq_qos *rqos, struct request *rq)
{
struct ioc *ioc = rqos_to_ioc(rqos);
- u64 on_q_ns, rq_wait_ns;
+ u64 on_q_ns, rq_wait_ns, size_nsec;
int pidx, rw;
if (!ioc->enabled || !rq->alloc_time_ns || !rq->start_time_ns)
@@ -1889,8 +1930,10 @@ static void ioc_rqos_done(struct rq_qos *rqos, struct request *rq)
on_q_ns = ktime_get_ns() - rq->alloc_time_ns;
rq_wait_ns = rq->start_time_ns - rq->alloc_time_ns;
+ size_nsec = div64_u64(calc_size_vtime_cost(rq, ioc), VTIME_PER_NSEC);
- if (on_q_ns <= ioc->params.qos[pidx] * NSEC_PER_USEC)
+ if (on_q_ns <= size_nsec ||
+ on_q_ns - size_nsec <= ioc->params.qos[pidx] * NSEC_PER_USEC)
this_cpu_inc(ioc->pcpu_stat->missed[rw].nr_met);
else
this_cpu_inc(ioc->pcpu_stat->missed[rw].nr_missed);
@@ -2297,6 +2340,7 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
spin_lock_irq(&ioc->lock);
if (enable) {
+ blk_stat_enable_accounting(ioc->rqos.q);
blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, ioc->rqos.q);
ioc->enabled = true;
} else {
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-10 19:36:58 +0000