I think what is happening here is that if a client has flows such as "a
(bulk upload)" and "b (bulk download)", the incoming ACKs of flow "a"
compete with the incoming bulk traffic on flow "b". With compete I mean
in terms of flow selection.
So if we adjust the host_load to be the same with the bulk_flow_count of
*each* host, the problem seems to be resolved.
I drafted a patch below.
Pete's setup, tested with the patch (ingress in mbit/s):
IP1: 8down 49.18mbit/s
IP1: 1up 46.73mbit/s
IP2: 1down 47.39mbit/s
IP2: 8up 49.21mbit/s
---
sch_cake.c | 34 ++++++++++++++++++++++++++++------
1 file changed, 28 insertions(+), 6 deletions(-)
diff --git a/sch_cake.c b/sch_cake.c
index d434ae0..5c0f0e1 100644
--- a/sch_cake.c
+++ b/sch_cake.c
@@ -148,6 +148,7 @@ struct cake_host {
u32 dsthost_tag;
u16 srchost_refcnt;
u16 dsthost_refcnt;
+ u16 bulk_flow_count;
};
struct cake_heap_entry {
@@ -1897,10 +1898,10 @@ static s32 cake_enqueue(struct sk_buff *skb, struct
Qdisc *sch,
q->last_packet_time = now;
}
+ struct cake_host *srchost = &b->hosts[flow->srchost];
+ struct cake_host *dsthost = &b->hosts[flow->dsthost];
/* flowchain */
if (!flow->set || flow->set == CAKE_SET_DECAYING) {
- struct cake_host *srchost = &b->hosts[flow->srchost];
- struct cake_host *dsthost = &b->hosts[flow->dsthost];
u16 host_load = 1;
if (!flow->set) {
@@ -1927,6 +1928,11 @@ static s32 cake_enqueue(struct sk_buff *skb, struct
Qdisc *sch,
flow->set = CAKE_SET_BULK;
b->sparse_flow_count--;
b->bulk_flow_count++;
+ if (cake_dsrc(q->flow_mode))
+ srchost->bulk_flow_count++;
+
+ if (cake_ddst(q->flow_mode))
+ dsthost->bulk_flow_count++;
}
if (q->buffer_used > q->buffer_max_used)
@@ -2101,7 +2107,7 @@ retry:
host_load = max(host_load, srchost->srchost_refcnt);
if (cake_ddst(q->flow_mode))
- host_load = max(host_load, dsthost->dsthost_refcnt);
+ host_load = max(host_load, dsthost->bulk_flow_count);
WARN_ON(host_load > CAKE_QUEUES);
@@ -2110,8 +2116,6 @@ retry:
/* The shifted prandom_u32() is a way to apply dithering to
* avoid accumulating roundoff errors
*/
- flow->deficit += (b->flow_quantum * quantum_div[host_load] +
- (prandom_u32() >> 16)) >> 16;
list_move_tail(&flow->flowchain, &b->old_flows);
/* Keep all flows with deficits out of the sparse and decaying
@@ -2122,6 +2126,11 @@ retry:
if (flow->head) {
b->sparse_flow_count--;
b->bulk_flow_count++;
+ if (cake_dsrc(q->flow_mode))
+ srchost->bulk_flow_count++;
+
+ if (cake_ddst(q->flow_mode))
+ dsthost->bulk_flow_count++;
flow->set = CAKE_SET_BULK;
} else {
/* we've moved it to the bulk rotation for
@@ -2131,6 +2140,8 @@ retry:
flow->set = CAKE_SET_SPARSE_WAIT;
}
}
+ flow->deficit += (b->flow_quantum * quantum_div[host_load] +
+ (prandom_u32() >> 16)) >> 16;
goto retry;
}
@@ -2151,6 +2162,11 @@ retry:
&b->decaying_flows);
if (flow->set == CAKE_SET_BULK) {
b->bulk_flow_count--;
+ if (cake_dsrc(q->flow_mode))
+ srchost->bulk_flow_count--;
+
+ if (cake_ddst(q->flow_mode))
+ dsthost->bulk_flow_count--;
b->decaying_flow_count++;
} else if (flow->set == CAKE_SET_SPARSE ||
flow->set == CAKE_SET_SPARSE_WAIT) {
@@ -2164,8 +2180,14 @@ retry:
if (flow->set == CAKE_SET_SPARSE ||
flow->set == CAKE_SET_SPARSE_WAIT)
b->sparse_flow_count--;
- else if (flow->set == CAKE_SET_BULK)
+ else if (flow->set == CAKE_SET_BULK) {
b->bulk_flow_count--;
+ if (cake_dsrc(q->flow_mode))
+ srchost->bulk_flow_count--;
+
+ if (cake_ddst(q->flow_mode))
+ dsthost->bulk_flow_count--;
+ }
else
b->decaying_flow_count--;
--
2.20.1
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