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authorFelix Fietkau <nbd@nbd.name>2018-03-10 10:09:07 +0100
committerFelix Fietkau <nbd@nbd.name>2018-03-11 09:30:28 +0100
commit60f8d388c69e0faddbf1c3033cdcb74b38fe3694 (patch)
treeb09988dfa4b298a48cd129ce46ef11c304417735
parentf609913b5c60f7c65c462730993cd1c752083fd6 (diff)
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kernel: merge a pending fix for HFSC warnings/slowdowns (fixes FS#1136)
Signed-off-by: Felix Fietkau <nbd@nbd.name>
-rw-r--r--target/linux/generic/patches-4.4/620-net_sched-codel-do-not-defer-queue-length-update.patch86
-rw-r--r--target/linux/generic/patches-4.4/660-fq_codel_defaults.patch2
-rw-r--r--target/linux/generic/patches-4.4/662-use_fq_codel_by_default.patch4
3 files changed, 89 insertions, 3 deletions
diff --git a/target/linux/generic/patches-4.4/620-net_sched-codel-do-not-defer-queue-length-update.patch b/target/linux/generic/patches-4.4/620-net_sched-codel-do-not-defer-queue-length-update.patch
new file mode 100644
index 0000000000..2ec9c7a9e2
--- /dev/null
+++ b/target/linux/generic/patches-4.4/620-net_sched-codel-do-not-defer-queue-length-update.patch
@@ -0,0 +1,86 @@
+From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Date: Mon, 21 Aug 2017 11:14:14 +0300
+Subject: [PATCH] net_sched/codel: do not defer queue length update
+
+When codel wants to drop last packet in ->dequeue() it cannot call
+qdisc_tree_reduce_backlog() right away - it will notify parent qdisc
+about zero qlen and HTB/HFSC will deactivate class. The same class will
+be deactivated second time by caller of ->dequeue(). Currently codel and
+fq_codel defer update. This triggers warning in HFSC when it's qlen != 0
+but there is no active classes.
+
+This patch update parent queue length immediately: just temporary increase
+qlen around qdisc_tree_reduce_backlog() to prevent first class deactivation
+if we have skb to return.
+
+This might open another problem in HFSC - now operation peek could fail and
+deactivate parent class.
+
+Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Link: https://bugzilla.kernel.org/show_bug.cgi?id=109581
+---
+
+--- a/net/sched/sch_codel.c
++++ b/net/sched/sch_codel.c
+@@ -79,11 +79,17 @@ static struct sk_buff *codel_qdisc_deque
+
+ skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue);
+
+- /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
+- * or HTB crashes. Defer it for next round.
++ /* If our qlen is 0 qdisc_tree_reduce_backlog() will deactivate
++ * parent class, dequeue in parent qdisc will do the same if we
++ * return skb. Temporary increment qlen if we have skb.
+ */
+- if (q->stats.drop_count && sch->q.qlen) {
+- qdisc_tree_reduce_backlog(sch, q->stats.drop_count, q->stats.drop_len);
++ if (q->stats.drop_count) {
++ if (skb)
++ sch->q.qlen++;
++ qdisc_tree_reduce_backlog(sch, q->stats.drop_count,
++ q->stats.drop_len);
++ if (skb)
++ sch->q.qlen--;
+ q->stats.drop_count = 0;
+ q->stats.drop_len = 0;
+ }
+--- a/net/sched/sch_fq_codel.c
++++ b/net/sched/sch_fq_codel.c
+@@ -311,6 +311,21 @@ begin:
+ flow->dropped += q->cstats.drop_count - prev_drop_count;
+ flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
+
++ /* If our qlen is 0 qdisc_tree_reduce_backlog() will deactivate
++ * parent class, dequeue in parent qdisc will do the same if we
++ * return skb. Temporary increment qlen if we have skb.
++ */
++ if (q->cstats.drop_count) {
++ if (skb)
++ sch->q.qlen++;
++ qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
++ q->cstats.drop_len);
++ if (skb)
++ sch->q.qlen--;
++ q->cstats.drop_count = 0;
++ q->cstats.drop_len = 0;
++ }
++
+ if (!skb) {
+ /* force a pass through old_flows to prevent starvation */
+ if ((head == &q->new_flows) && !list_empty(&q->old_flows))
+@@ -321,15 +336,6 @@ begin:
+ }
+ qdisc_bstats_update(sch, skb);
+ flow->deficit -= qdisc_pkt_len(skb);
+- /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
+- * or HTB crashes. Defer it for next round.
+- */
+- if (q->cstats.drop_count && sch->q.qlen) {
+- qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
+- q->cstats.drop_len);
+- q->cstats.drop_count = 0;
+- q->cstats.drop_len = 0;
+- }
+ return skb;
+ }
+
diff --git a/target/linux/generic/patches-4.4/660-fq_codel_defaults.patch b/target/linux/generic/patches-4.4/660-fq_codel_defaults.patch
index 46fceffcf1..fbe900891c 100644
--- a/target/linux/generic/patches-4.4/660-fq_codel_defaults.patch
+++ b/target/linux/generic/patches-4.4/660-fq_codel_defaults.patch
@@ -1,6 +1,6 @@
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
-@@ -471,7 +471,7 @@ static int fq_codel_init(struct Qdisc *s
+@@ -477,7 +477,7 @@ static int fq_codel_init(struct Qdisc *s
sch->limit = 10*1024;
q->flows_cnt = 1024;
diff --git a/target/linux/generic/patches-4.4/662-use_fq_codel_by_default.patch b/target/linux/generic/patches-4.4/662-use_fq_codel_by_default.patch
index 9d1962caa9..8d70b82350 100644
--- a/target/linux/generic/patches-4.4/662-use_fq_codel_by_default.patch
+++ b/target/linux/generic/patches-4.4/662-use_fq_codel_by_default.patch
@@ -13,7 +13,7 @@
device, it has to decide which ones to send first, which ones to
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
-@@ -688,7 +688,7 @@ static const struct Qdisc_class_ops fq_c
+@@ -694,7 +694,7 @@ static const struct Qdisc_class_ops fq_c
.walk = fq_codel_walk,
};
@@ -22,7 +22,7 @@
.cl_ops = &fq_codel_class_ops,
.id = "fq_codel",
.priv_size = sizeof(struct fq_codel_sched_data),
-@@ -704,6 +704,7 @@ static struct Qdisc_ops fq_codel_qdisc_o
+@@ -710,6 +710,7 @@ static struct Qdisc_ops fq_codel_qdisc_o
.dump_stats = fq_codel_dump_stats,
.owner = THIS_MODULE,
};