mac80211: implement codel on fair queuing flows
There is no other limit other than a global
packet count limit when using software queuing.
This means a single flow queue can grow insanely
long. This is particularly bad for TCP congestion
algorithms which requires a little more
sophisticated frame dropping scheme than a mere
headdrop on limit overflow.
Hence apply (a slighly modified, to fit the knobs)
CoDel5 on flow queues. This improves TCP
convergence and stability when combined with
wireless driver which keeps its own tx queue/fifo
at a minimum fill level for given link conditions.
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 1d8343f..44ec605 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -24,6 +24,8 @@
#include <net/ieee80211_radiotap.h>
#include <net/cfg80211.h>
#include <net/mac80211.h>
+#include <net/codel.h>
+#include <net/codel_impl.h>
#include <asm/unaligned.h>
#include <net/fq_impl.h>
@@ -1267,11 +1269,92 @@
return to_txq_info(txq);
}
+static void ieee80211_set_skb_enqueue_time(struct sk_buff *skb)
+{
+ IEEE80211_SKB_CB(skb)->control.enqueue_time = codel_get_time();
+}
+
+static void ieee80211_set_skb_vif(struct sk_buff *skb, struct txq_info *txqi)
+{
+ IEEE80211_SKB_CB(skb)->control.vif = txqi->txq.vif;
+}
+
+static u32 codel_skb_len_func(const struct sk_buff *skb)
+{
+ return skb->len;
+}
+
+static codel_time_t codel_skb_time_func(const struct sk_buff *skb)
+{
+ const struct ieee80211_tx_info *info;
+
+ info = (const struct ieee80211_tx_info *)skb->cb;
+ return info->control.enqueue_time;
+}
+
+static struct sk_buff *codel_dequeue_func(struct codel_vars *cvars,
+ void *ctx)
+{
+ struct ieee80211_local *local;
+ struct txq_info *txqi;
+ struct fq *fq;
+ struct fq_flow *flow;
+
+ txqi = ctx;
+ local = vif_to_sdata(txqi->txq.vif)->local;
+ fq = &local->fq;
+
+ if (cvars == &txqi->def_cvars)
+ flow = &txqi->def_flow;
+ else
+ flow = &fq->flows[cvars - local->cvars];
+
+ return fq_flow_dequeue(fq, flow);
+}
+
+static void codel_drop_func(struct sk_buff *skb,
+ void *ctx)
+{
+ struct ieee80211_local *local;
+ struct ieee80211_hw *hw;
+ struct txq_info *txqi;
+
+ txqi = ctx;
+ local = vif_to_sdata(txqi->txq.vif)->local;
+ hw = &local->hw;
+
+ ieee80211_free_txskb(hw, skb);
+}
+
static struct sk_buff *fq_tin_dequeue_func(struct fq *fq,
struct fq_tin *tin,
struct fq_flow *flow)
{
- return fq_flow_dequeue(fq, flow);
+ struct ieee80211_local *local;
+ struct txq_info *txqi;
+ struct codel_vars *cvars;
+ struct codel_params *cparams;
+ struct codel_stats *cstats;
+
+ local = container_of(fq, struct ieee80211_local, fq);
+ txqi = container_of(tin, struct txq_info, tin);
+ cparams = &local->cparams;
+ cstats = &local->cstats;
+
+ if (flow == &txqi->def_flow)
+ cvars = &txqi->def_cvars;
+ else
+ cvars = &local->cvars[flow - fq->flows];
+
+ return codel_dequeue(txqi,
+ &flow->backlog,
+ cparams,
+ cvars,
+ cstats,
+ codel_skb_len_func,
+ codel_skb_time_func,
+ codel_drop_func,
+ codel_dequeue_func);
}
static void fq_skb_free_func(struct fq *fq,
@@ -1303,6 +1386,7 @@
struct fq *fq = &local->fq;
struct fq_tin *tin = &txqi->tin;
+ ieee80211_set_skb_enqueue_time(skb);
fq_tin_enqueue(fq, tin, skb,
fq_skb_free_func,
fq_flow_get_default_func);
@@ -1314,6 +1398,7 @@
{
fq_tin_init(&txqi->tin);
fq_flow_init(&txqi->def_flow);
+ codel_vars_init(&txqi->def_cvars);
txqi->txq.vif = &sdata->vif;
@@ -1342,6 +1427,7 @@
{
struct fq *fq = &local->fq;
int ret;
+ int i;
if (!local->ops->wake_tx_queue)
return 0;
@@ -1350,6 +1436,22 @@
if (ret)
return ret;
+ codel_params_init(&local->cparams);
+ codel_stats_init(&local->cstats);
+ local->cparams.interval = MS2TIME(100);
+ local->cparams.target = MS2TIME(20);
+ local->cparams.ecn = true;
+
+ local->cvars = kcalloc(fq->flows_cnt, sizeof(local->cvars[0]),
+ GFP_KERNEL);
+ if (!local->cvars) {
+ fq_reset(fq, fq_skb_free_func);
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < fq->flows_cnt; i++)
+ codel_vars_init(&local->cvars[i]);
+
return 0;
}
@@ -1360,6 +1462,9 @@
if (!local->ops->wake_tx_queue)
return;
+ kfree(local->cvars);
+ local->cvars = NULL;
+
fq_reset(fq, fq_skb_free_func);
}
@@ -1382,6 +1487,8 @@
if (!skb)
goto out;
+ ieee80211_set_skb_vif(skb, txqi);
+
hdr = (struct ieee80211_hdr *)skb->data;
if (txq->sta && ieee80211_is_data_qos(hdr->frame_control)) {
struct sta_info *sta = container_of(txq->sta, struct sta_info,