aboutsummaryrefslogtreecommitdiffstats
path: root/target/linux/generic/patches-4.4/033-fq_codel-add-memory-limitation-per-queue.patch
blob: 455add9eae8bbdc51b6cd3107556548c8981f256 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
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++;