kernel: backport patches for fq_codel queue memory limit support

Use it to replace the reduction in max packets/flows

Signed-off-by: Felix Fietkau <nbd@nbd.name>

1 files changed, 182 insertions, 0 deletions

diff --git a/target/linux/generic/patches-4.4/033-fq_codel-add-memory-limitation-per-queue.patch b/target/linux/generic/patches-4.4/033-fq_codel-add-memory-limitation-per-queue.patch
new file mode 100644
index 0000000000..455add9eae
--- /dev/null
+++ b/target/linux/generic/patches-4.4/033-fq_codel-add-memory-limitation-per-queue.patch
@@ -0,0 +1,182 @@
+From: Eric Dumazet <edumazet@google.com>
+Date: Fri, 6 May 2016 08:55:12 -0700
+Subject: [PATCH] fq_codel: add memory limitation per queue
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+On small embedded routers, one wants to control maximal amount of
+memory used by fq_codel, instead of controlling number of packets or
+bytes, since GRO/TSO make these not practical.
+
+Assuming skb->truesize is accurate, we have to keep track of
+skb->truesize sum for skbs in queue.
+
+This patch adds a new TCA_FQ_CODEL_MEMORY_LIMIT attribute.
+
+I chose a default value of 32 MBytes, which looks reasonable even
+for heavy duty usages. (Prior fq_codel users should not be hurt
+when they upgrade their kernels)
+
+Two fields are added to tc_fq_codel_qd_stats to report :
+ - Current memory usage
+ - Number of drops caused by memory limits
+
+# tc qd replace dev eth1 root est 1sec 4sec fq_codel memory_limit 4M
+..
+# tc -s -d qd sh dev eth1
+qdisc fq_codel 8008: root refcnt 257 limit 10240p flows 1024
+ quantum 1514 target 5.0ms interval 100.0ms memory_limit 4Mb ecn
+ Sent 2083566791363 bytes 1376214889 pkt (dropped 4994406, overlimits 0
+requeues 21705223)
+ rate 9841Mbit 812549pps backlog 3906120b 376p requeues 21705223
+  maxpacket 68130 drop_overlimit 4994406 new_flow_count 28855414
+  ecn_mark 0 memory_used 4190048 drop_overmemory 4994406
+  new_flows_len 1 old_flows_len 177
+
+Signed-off-by: Eric Dumazet <edumazet@google.com>
+Cc: Jesper Dangaard Brouer <brouer@redhat.com>
+Cc: Dave Täht <dave.taht@gmail.com>
+Cc: Sebastian Möller <moeller0@gmx.de>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+
+--- a/include/uapi/linux/pkt_sched.h
++++ b/include/uapi/linux/pkt_sched.h
+@@ -712,6 +712,7 @@ enum {
+ 	TCA_FQ_CODEL_QUANTUM,
+ 	TCA_FQ_CODEL_CE_THRESHOLD,
+ 	TCA_FQ_CODEL_DROP_BATCH_SIZE,
++	TCA_FQ_CODEL_MEMORY_LIMIT,
+ 	__TCA_FQ_CODEL_MAX
+ };
+ 
+@@ -736,6 +737,8 @@ struct tc_fq_codel_qd_stats {
+ 	__u32	new_flows_len;	/* count of flows in new list */
+ 	__u32	old_flows_len;	/* count of flows in old list */
+ 	__u32	ce_mark;	/* packets above ce_threshold */
++	__u32	memory_usage;	/* in bytes */
++	__u32	drop_overmemory;
+ };
+ 
+ struct tc_fq_codel_cl_stats {
+--- a/net/sched/sch_fq_codel.c
++++ b/net/sched/sch_fq_codel.c
+@@ -58,8 +58,11 @@ struct fq_codel_sched_data {
+ 	u32		perturbation;	/* hash perturbation */
+ 	u32		quantum;	/* psched_mtu(qdisc_dev(sch)); */
+ 	u32		drop_batch_size;
++	u32		memory_limit;
+ 	struct codel_params cparams;
+ 	struct codel_stats cstats;
++	u32		memory_usage;
++	u32		drop_overmemory;
+ 	u32		drop_overlimit;
+ 	u32		new_flow_count;
+ 
+@@ -141,6 +144,7 @@ static unsigned int fq_codel_drop(struct
+ 	unsigned int maxbacklog = 0, idx = 0, i, len;
+ 	struct fq_codel_flow *flow;
+ 	unsigned int threshold;
++	unsigned int mem = 0;
+ 
+ 	/* Queue is full! Find the fat flow and drop packet(s) from it.
+ 	 * This might sound expensive, but with 1024 flows, we scan
+@@ -165,11 +169,13 @@ static unsigned int fq_codel_drop(struct
+ 	do {
+ 		skb = dequeue_head(flow);
+ 		len += qdisc_pkt_len(skb);
++		mem += skb->truesize;
+ 		kfree_skb(skb);
+ 	} while (++i < max_packets && len < threshold);
+ 
+ 	flow->dropped += i;
+ 	q->backlogs[idx] -= len;
++	q->memory_usage -= mem;
+ 	sch->qstats.drops += i;
+ 	sch->qstats.backlog -= len;
+ 	sch->q.qlen -= i;
+@@ -191,6 +197,7 @@ static int fq_codel_enqueue(struct sk_bu
+ 	unsigned int idx, prev_backlog, prev_qlen;
+ 	struct fq_codel_flow *flow;
+ 	int uninitialized_var(ret);
++	bool memory_limited;
+ 
+ 	idx = fq_codel_classify(skb, sch, &ret);
+ 	if (idx == 0) {
+@@ -213,7 +220,9 @@ static int fq_codel_enqueue(struct sk_bu
+ 		flow->deficit = q->quantum;
+ 		flow->dropped = 0;
+ 	}
+-	if (++sch->q.qlen <= sch->limit)
++	q->memory_usage += skb->truesize;
++	memory_limited = q->memory_usage > q->memory_limit;
++	if (++sch->q.qlen <= sch->limit && !memory_limited)
+ 		return NET_XMIT_SUCCESS;
+ 
+ 	prev_backlog = sch->qstats.backlog;
+@@ -227,7 +236,8 @@ static int fq_codel_enqueue(struct sk_bu
+ 	ret = fq_codel_drop(sch, q->drop_batch_size);
+ 
+ 	q->drop_overlimit += prev_qlen - sch->q.qlen;
+-
++	if (memory_limited)
++		q->drop_overmemory += prev_qlen - sch->q.qlen;
+ 	/* As we dropped packet(s), better let upper stack know this */
+ 	qdisc_tree_reduce_backlog(sch, prev_qlen - sch->q.qlen,
+ 				  prev_backlog - sch->qstats.backlog);
+@@ -296,6 +306,7 @@ begin:
+ 			list_del_init(&flow->flowchain);
+ 		goto begin;
+ 	}
++	q->memory_usage -= skb->truesize;
+ 	qdisc_bstats_update(sch, skb);
+ 	flow->deficit -= qdisc_pkt_len(skb);
+ 	/* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
+@@ -343,6 +354,7 @@ static const struct nla_policy fq_codel_
+ 	[TCA_FQ_CODEL_QUANTUM]	= { .type = NLA_U32 },
+ 	[TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },
+ 	[TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },
++	[TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },
+ };
+ 
+ static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt)
+@@ -397,7 +409,11 @@ static int fq_codel_change(struct Qdisc
+ 	if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
+ 		q->drop_batch_size = min(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
+ 
+-	while (sch->q.qlen > sch->limit) {
++	if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
++		q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
++
++	while (sch->q.qlen > sch->limit ||
++	       q->memory_usage > q->memory_limit) {
+ 		struct sk_buff *skb = fq_codel_dequeue(sch);
+ 
+ 		q->cstats.drop_len += qdisc_pkt_len(skb);
+@@ -442,6 +458,7 @@ static int fq_codel_init(struct Qdisc *s
+ 
+ 	sch->limit = 10*1024;
+ 	q->flows_cnt = 1024;
++	q->memory_limit = 32 << 20; /* 32 MBytes */
+ 	q->drop_batch_size = 64;
+ 	q->quantum = psched_mtu(qdisc_dev(sch));
+ 	q->perturbation = prandom_u32();
+@@ -502,6 +519,8 @@ static int fq_codel_dump(struct Qdisc *s
+ 			q->quantum) ||
+ 	    nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
+ 			q->drop_batch_size) ||
++	    nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
++			q->memory_limit) ||
+ 	    nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
+ 			q->flows_cnt))
+ 		goto nla_put_failure;
+@@ -530,6 +549,8 @@ static int fq_codel_dump_stats(struct Qd
+ 	st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
+ 	st.qdisc_stats.new_flow_count = q->new_flow_count;
+ 	st.qdisc_stats.ce_mark = q->cstats.ce_mark;
++	st.qdisc_stats.memory_usage  = q->memory_usage;
++	st.qdisc_stats.drop_overmemory = q->drop_overmemory;
+ 
+ 	list_for_each(pos, &q->new_flows)
+ 		st.qdisc_stats.new_flows_len++;