Instead of marking iocgs with surplus with a flag and filtering for them
while walking all active iocgs, build a surpluses list. This doesn't make
much difference now but will help implementing improved donation logic which
will iterate iocgs with surplus multiple times.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
block/blk-iocost.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 2496674bbbf4..c1cd66cfa2a8 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -494,9 +494,9 @@ struct ioc_gq {
int hweight_gen;
u32 hweight_active;
u32 hweight_inuse;
- bool has_surplus;
struct list_head walk_list;
+ struct list_head surplus_list;
struct wait_queue_head waitq;
struct hrtimer waitq_timer;
@@ -1507,6 +1507,7 @@ static void ioc_timer_fn(struct timer_list *timer)
struct ioc *ioc = container_of(timer, struct ioc, timer);
struct ioc_gq *iocg, *tiocg;
struct ioc_now now;
+ LIST_HEAD(surpluses);
int nr_surpluses = 0, nr_shortages = 0, nr_lagging = 0;
u32 ppm_rthr = MILLION - ioc->params.qos[QOS_RPPM];
u32 ppm_wthr = MILLION - ioc->params.qos[QOS_WPPM];
@@ -1630,8 +1631,7 @@ static void ioc_timer_fn(struct timer_list *timer)
/* see whether there's surplus vtime */
vmin = now.vnow - ioc->margins.max;
- iocg->has_surplus = false;
-
+ WARN_ON_ONCE(!list_empty(&iocg->surplus_list));
if (!waitqueue_active(&iocg->waitq) &&
time_before64(vtime, vmin)) {
u64 delta = vmin - vtime;
@@ -1641,7 +1641,7 @@ static void ioc_timer_fn(struct timer_list *timer)
atomic64_add(delta, &iocg->done_vtime);
/* if usage is sufficiently low, maybe it can donate */
if (surplus_adjusted_hweight_inuse(usage, hw_inuse)) {
- iocg->has_surplus = true;
+ list_add(&iocg->surplus_list, &surpluses);
nr_surpluses++;
}
} else if (hw_inuse < hw_active) {
@@ -1677,13 +1677,10 @@ static void ioc_timer_fn(struct timer_list *timer)
goto skip_surplus_transfers;
/* there are both shortages and surpluses, transfer surpluses */
- list_for_each_entry(iocg, &ioc->active_iocgs, active_list) {
+ list_for_each_entry(iocg, &surpluses, surplus_list) {
u32 usage, hw_active, hw_inuse, new_hwi, new_inuse;
int nr_valid = 0;
- if (!iocg->has_surplus)
- continue;
-
/* base the decision on max historical usage */
for (i = 0, usage = 0; i < NR_USAGE_SLOTS; i++) {
if (iocg->usages[i]) {
@@ -1711,6 +1708,10 @@ static void ioc_timer_fn(struct timer_list *timer)
skip_surplus_transfers:
commit_weights(ioc);
+ /* surplus list should be dissolved after use */
+ list_for_each_entry_safe(iocg, tiocg, &surpluses, surplus_list)
+ list_del_init(&iocg->surplus_list);
+
/*
* If q is getting clogged or we're missing too much, we're issuing
* too much IO and should lower vtime rate. If we're not missing
@@ -2284,6 +2285,7 @@ static void ioc_pd_init(struct blkg_policy_data *pd)
atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period));
INIT_LIST_HEAD(&iocg->active_list);
INIT_LIST_HEAD(&iocg->walk_list);
+ INIT_LIST_HEAD(&iocg->surplus_list);
iocg->hweight_active = WEIGHT_ONE;
iocg->hweight_inuse = WEIGHT_ONE;
@@ -2320,6 +2322,7 @@ static void ioc_pd_free(struct blkg_policy_data *pd)
}
WARN_ON_ONCE(!list_empty(&iocg->walk_list));
+ WARN_ON_ONCE(!list_empty(&iocg->surplus_list));
spin_unlock_irqrestore(&ioc->lock, flags);
--
2.26.2
