[Cake] progress? dual-src/dsthost unfairness
George Amanakis
gamanakis at gmail.com
Wed Feb 13 13:31:32 EST 2019
I recently rewrote the patch (out-of-tree cake) so as to keep track of the
bulk/sparse flow-count per host. I have been testing it for about a month
on a WRT1900ACS and it runs fine.
Would love to hear if Jonathan or anybody else has thought of
implementing something different.
Best,
George
---
sch_cake.c | 120 +++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 88 insertions(+), 32 deletions(-)
diff --git a/sch_cake.c b/sch_cake.c
index d434ae0..10364ec 100644
--- a/sch_cake.c
+++ b/sch_cake.c
@@ -146,8 +146,10 @@ struct cake_flow {
struct cake_host {
u32 srchost_tag;
u32 dsthost_tag;
- u16 srchost_refcnt;
- u16 dsthost_refcnt;
+ u16 srchost_bulk_flow_count;
+ u16 srchost_sparse_flow_count;
+ u16 dsthost_bulk_flow_count;
+ u16 dsthost_sparse_flow_count;
};
struct cake_heap_entry {
@@ -844,8 +846,6 @@ skip_hash:
* queue, accept the collision, update the host tags.
*/
q->way_collisions++;
- q->hosts[q->flows[reduced_hash].srchost].srchost_refcnt--;
- q->hosts[q->flows[reduced_hash].dsthost].dsthost_refcnt--;
allocate_src = cake_dsrc(flow_mode);
allocate_dst = cake_ddst(flow_mode);
found:
@@ -865,13 +865,13 @@ found:
}
for (i = 0; i < CAKE_SET_WAYS;
i++, k = (k + 1) % CAKE_SET_WAYS) {
- if (!q->hosts[outer_hash + k].srchost_refcnt)
+ if (!q->hosts[outer_hash + k].srchost_bulk_flow_count &&
+ !q->hosts[outer_hash + k].srchost_sparse_flow_count)
break;
}
q->hosts[outer_hash + k].srchost_tag = srchost_hash;
found_src:
srchost_idx = outer_hash + k;
- q->hosts[srchost_idx].srchost_refcnt++;
q->flows[reduced_hash].srchost = srchost_idx;
}
@@ -887,13 +887,13 @@ found_src:
}
for (i = 0; i < CAKE_SET_WAYS;
i++, k = (k + 1) % CAKE_SET_WAYS) {
- if (!q->hosts[outer_hash + k].dsthost_refcnt)
+ if (!q->hosts[outer_hash + k].dsthost_bulk_flow_count &&
+ !q->hosts[outer_hash + k].dsthost_sparse_flow_count)
break;
}
q->hosts[outer_hash + k].dsthost_tag = dsthost_hash;
found_dst:
dsthost_idx = outer_hash + k;
- q->hosts[dsthost_idx].dsthost_refcnt++;
q->flows[reduced_hash].dsthost = dsthost_idx;
}
}
@@ -1912,21 +1912,39 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch,
flow->set = CAKE_SET_SPARSE;
b->sparse_flow_count++;
- if (cake_dsrc(q->flow_mode))
- host_load = max(host_load, srchost->srchost_refcnt);
+ if (cake_dsrc(q->flow_mode)) {
+ srchost->srchost_sparse_flow_count++;
+ host_load = max(host_load, srchost->srchost_sparse_flow_count);
+ }
- if (cake_ddst(q->flow_mode))
- host_load = max(host_load, dsthost->dsthost_refcnt);
+ if (cake_ddst(q->flow_mode)) {
+ dsthost->dsthost_sparse_flow_count++;
+ host_load = max(host_load, dsthost->dsthost_sparse_flow_count);
+ }
flow->deficit = (b->flow_quantum *
quantum_div[host_load]) >> 16;
} else if (flow->set == CAKE_SET_SPARSE_WAIT) {
+ struct cake_host *srchost = &b->hosts[flow->srchost];
+ struct cake_host *dsthost = &b->hosts[flow->dsthost];
+
/* this flow was empty, accounted as a sparse flow, but actually
* in the bulk rotation.
*/
flow->set = CAKE_SET_BULK;
b->sparse_flow_count--;
b->bulk_flow_count++;
+
+ if (cake_dsrc(q->flow_mode)) {
+ srchost->srchost_sparse_flow_count--;
+ srchost->srchost_bulk_flow_count++;
+ }
+
+ if (cake_ddst(q->flow_mode)) {
+ dsthost->dsthost_sparse_flow_count--;
+ dsthost->dsthost_bulk_flow_count++;
+ }
+
}
if (q->buffer_used > q->buffer_max_used)
@@ -2097,23 +2115,8 @@ retry:
dsthost = &b->hosts[flow->dsthost];
host_load = 1;
- if (cake_dsrc(q->flow_mode))
- host_load = max(host_load, srchost->srchost_refcnt);
-
- if (cake_ddst(q->flow_mode))
- host_load = max(host_load, dsthost->dsthost_refcnt);
-
- WARN_ON(host_load > CAKE_QUEUES);
-
/* flow isolation (DRR++) */
if (flow->deficit <= 0) {
- /* 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
* rotations. No non-empty flow can go into the decaying
* rotation, so they can't get deficits
@@ -2122,6 +2125,17 @@ retry:
if (flow->head) {
b->sparse_flow_count--;
b->bulk_flow_count++;
+
+ if (cake_dsrc(q->flow_mode)) {
+ srchost->srchost_sparse_flow_count--;
+ srchost->srchost_bulk_flow_count++;
+ }
+
+ if (cake_ddst(q->flow_mode)) {
+ dsthost->dsthost_sparse_flow_count--;
+ dsthost->dsthost_bulk_flow_count++;
+ }
+
flow->set = CAKE_SET_BULK;
} else {
/* we've moved it to the bulk rotation for
@@ -2131,6 +2145,22 @@ retry:
flow->set = CAKE_SET_SPARSE_WAIT;
}
}
+
+ if (cake_dsrc(q->flow_mode))
+ host_load = max(host_load, srchost->srchost_bulk_flow_count);
+
+ if (cake_ddst(q->flow_mode))
+ host_load = max(host_load, dsthost->dsthost_bulk_flow_count);
+
+ WARN_ON(host_load > CAKE_QUEUES);
+
+ /* 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);
+
goto retry;
}
@@ -2151,10 +2181,24 @@ retry:
&b->decaying_flows);
if (flow->set == CAKE_SET_BULK) {
b->bulk_flow_count--;
+
+ if (cake_dsrc(q->flow_mode))
+ srchost->srchost_bulk_flow_count--;
+
+ if (cake_ddst(q->flow_mode))
+ dsthost->dsthost_bulk_flow_count--;
+
b->decaying_flow_count++;
} else if (flow->set == CAKE_SET_SPARSE ||
flow->set == CAKE_SET_SPARSE_WAIT) {
b->sparse_flow_count--;
+
+ if (cake_dsrc(q->flow_mode))
+ srchost->srchost_sparse_flow_count--;
+
+ if (cake_ddst(q->flow_mode))
+ dsthost->dsthost_sparse_flow_count--;
+
b->decaying_flow_count++;
}
flow->set = CAKE_SET_DECAYING;
@@ -2162,16 +2206,28 @@ retry:
/* remove empty queue from the flowchain */
list_del_init(&flow->flowchain);
if (flow->set == CAKE_SET_SPARSE ||
- flow->set == CAKE_SET_SPARSE_WAIT)
+ flow->set == CAKE_SET_SPARSE_WAIT) {
b->sparse_flow_count--;
- else if (flow->set == CAKE_SET_BULK)
+
+ if (cake_dsrc(q->flow_mode))
+ srchost->srchost_sparse_flow_count--;
+
+ if (cake_ddst(q->flow_mode))
+ dsthost->dsthost_sparse_flow_count--;
+
+ } else if (flow->set == CAKE_SET_BULK) {
b->bulk_flow_count--;
- else
+
+ if (cake_dsrc(q->flow_mode))
+ srchost->srchost_bulk_flow_count--;
+
+ if (cake_ddst(q->flow_mode))
+ dsthost->dsthost_bulk_flow_count--;
+
+ } else
b->decaying_flow_count--;
flow->set = CAKE_SET_NONE;
- srchost->srchost_refcnt--;
- dsthost->dsthost_refcnt--;
}
goto begin;
}
--
2.20.1
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