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