#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/codel.h>
+#include <net/codel_impl.h>
+#include <net/codel_qdisc.h>
/* Fair Queue CoDel.
*
u32 flows_cnt; /* number of flows */
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;
skb->next = NULL;
}
-static unsigned int fq_codel_drop(struct Qdisc *sch)
+static unsigned int fq_codel_drop(struct Qdisc *sch, unsigned int max_packets)
{
struct fq_codel_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb;
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 from it.
+ /* Queue is full! Find the fat flow and drop packet(s) from it.
* This might sound expensive, but with 1024 flows, we scan
* 4KB of memory, and we dont need to handle a complex tree
* in fast path (packet queue/enqueue) with many cache misses.
+ * In stress mode, we'll try to drop 64 packets from the flow,
+ * amortizing this linear lookup to one cache line per drop.
*/
for (i = 0; i < q->flows_cnt; i++) {
if (q->backlogs[i] > maxbacklog) {
idx = i;
}
}
+
+ /* Our goal is to drop half of this fat flow backlog */
+ threshold = maxbacklog >> 1;
+
flow = &q->flows[idx];
- skb = dequeue_head(flow);
- len = qdisc_pkt_len(skb);
+ len = 0;
+ i = 0;
+ 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;
- sch->q.qlen--;
- qdisc_qstats_drop(sch);
- qdisc_qstats_backlog_dec(sch, skb);
- kfree_skb(skb);
- flow->dropped++;
+ q->memory_usage -= mem;
+ sch->qstats.drops += i;
+ sch->qstats.backlog -= len;
+ sch->q.qlen -= i;
return idx;
}
unsigned int prev_backlog;
prev_backlog = sch->qstats.backlog;
- fq_codel_drop(sch);
+ fq_codel_drop(sch, 1U);
return prev_backlog - sch->qstats.backlog;
}
static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
struct fq_codel_sched_data *q = qdisc_priv(sch);
- unsigned int idx, prev_backlog;
+ unsigned int idx, prev_backlog, prev_qlen;
struct fq_codel_flow *flow;
int uninitialized_var(ret);
+ unsigned int pkt_len;
+ bool memory_limited;
idx = fq_codel_classify(skb, sch, &ret);
if (idx == 0) {
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;
- q->drop_overlimit++;
- /* Return Congestion Notification only if we dropped a packet
- * from this flow.
+ prev_qlen = sch->q.qlen;
+
+ /* save this packet length as it might be dropped by fq_codel_drop() */
+ pkt_len = qdisc_pkt_len(skb);
+ /* fq_codel_drop() is quite expensive, as it performs a linear search
+ * in q->backlogs[] to find a fat flow.
+ * So instead of dropping a single packet, drop half of its backlog
+ * with a 64 packets limit to not add a too big cpu spike here.
*/
- if (fq_codel_drop(sch) == idx)
- return NET_XMIT_CN;
+ ret = fq_codel_drop(sch, q->drop_batch_size);
- /* As we dropped a packet, better let upper stack know this */
- qdisc_tree_reduce_backlog(sch, 1, prev_backlog - sch->qstats.backlog);
+ prev_qlen -= sch->q.qlen;
+ prev_backlog -= sch->qstats.backlog;
+ q->drop_overlimit += prev_qlen;
+ if (memory_limited)
+ q->drop_overmemory += prev_qlen;
+
+ /* As we dropped packet(s), better let upper stack know this.
+ * If we dropped a packet for this flow, return NET_XMIT_CN,
+ * but in this case, our parents wont increase their backlogs.
+ */
+ if (ret == idx) {
+ qdisc_tree_reduce_backlog(sch, prev_qlen - 1,
+ prev_backlog - pkt_len);
+ return NET_XMIT_CN;
+ }
+ qdisc_tree_reduce_backlog(sch, prev_qlen, prev_backlog);
return NET_XMIT_SUCCESS;
}
* to dequeue a packet from queue. Note: backlog is handled in
* codel, we dont need to reduce it here.
*/
-static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
+static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
{
+ struct Qdisc *sch = ctx;
struct fq_codel_sched_data *q = qdisc_priv(sch);
struct fq_codel_flow *flow;
struct sk_buff *skb = NULL;
if (flow->head) {
skb = dequeue_head(flow);
q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
+ q->memory_usage -= skb->truesize;
sch->q.qlen--;
+ sch->qstats.backlog -= qdisc_pkt_len(skb);
}
return skb;
}
+static void drop_func(struct sk_buff *skb, void *ctx)
+{
+ struct Qdisc *sch = ctx;
+
+ qdisc_drop(skb, sch);
+}
+
static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
{
struct fq_codel_sched_data *q = qdisc_priv(sch);
prev_ecn_mark = q->cstats.ecn_mark;
prev_backlog = sch->qstats.backlog;
- skb = codel_dequeue(sch, &q->cparams, &flow->cvars, &q->cstats,
- dequeue);
+ skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
+ &flow->cvars, &q->cstats, qdisc_pkt_len,
+ codel_get_enqueue_time, drop_func, dequeue_func);
flow->dropped += q->cstats.drop_count - prev_drop_count;
flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
}
memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
sch->q.qlen = 0;
+ q->memory_usage = 0;
}
static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
[TCA_FQ_CODEL_FLOWS] = { .type = NLA_U32 },
[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)
if (tb[TCA_FQ_CODEL_QUANTUM])
q->quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
- while (sch->q.qlen > sch->limit) {
+ if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
+ q->drop_batch_size = min(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
+
+ 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);
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();
INIT_LIST_HEAD(&q->new_flows);
INIT_LIST_HEAD(&q->old_flows);
- codel_params_init(&q->cparams, sch);
+ codel_params_init(&q->cparams);
codel_stats_init(&q->cstats);
q->cparams.ecn = true;
+ q->cparams.mtu = psched_mtu(qdisc_dev(sch));
if (opt) {
int err = fq_codel_change(sch, opt);
q->cparams.ecn) ||
nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
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;
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++;
qs.backlog = q->backlogs[idx];
qs.drops = flow->dropped;
}
- if (gnet_stats_copy_queue(d, NULL, &qs, 0) < 0)
+ if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
return -1;
if (idx < q->flows_cnt)
return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
projects / cascardo / linux.git / blobdiff