mac80211: Tx frame latency statistics

Measure TX latency and jitter statistics per station per TID.
These Measurements are disabled by default and can be enabled
via debugfs.

Features included for each station's TID:

1. Keep count of the maximum and average latency of Tx frames.
2. Keep track of many frames arrived in a specific time range
   (need to enable through debugfs and configure the bins ranges)

Signed-off-by: Matti Gottlieb <matti.gottlieb@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 7b69d4c3db55..8ed97f76c3cf 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -266,9 +266,17 @@ struct sta_info *sta_info_get_by_idx(struct ieee80211_sub_if_data *sdata,
  */
 void sta_info_free(struct ieee80211_local *local, struct sta_info *sta)
 {
+        int i;
+
         if (sta->rate_ctrl)
                 rate_control_free_sta(sta);
 
+        if (sta->tx_lat) {
+                for (i = 0; i < IEEE80211_NUM_TIDS; i++)
+                        kfree(sta->tx_lat[i].bins);
+                kfree(sta->tx_lat);
+        }
+
         sta_dbg(sta->sdata, "Destroyed STA %pM\n", sta->sta.addr);
 
         kfree(sta);
@@ -333,6 +341,7 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
         struct ieee80211_local *local = sdata->local;
         struct sta_info *sta;
         struct timespec uptime;
+        struct ieee80211_tx_latency_bin_ranges *tx_latency;
         int i;
 
         sta = kzalloc(sizeof(*sta) + local->hw.sta_data_size, gfp);
@@ -410,6 +419,31 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
                 }
         }
 
+        rcu_read_lock();
+
+        tx_latency = rcu_dereference(local->tx_latency);
+        /* init stations Tx latency statistics && TID bins */
+        if (tx_latency)
+                sta->tx_lat = kzalloc(IEEE80211_NUM_TIDS *
+                                      sizeof(struct ieee80211_tx_latency_stat),
+                                      GFP_ATOMIC);
+
+        /*
+         * if Tx latency and bins are enabled and the previous allocation
+         * succeeded
+         */
+        if (tx_latency && tx_latency->n_ranges && sta->tx_lat)
+                for (i = 0; i < IEEE80211_NUM_TIDS; i++) {
+                        /* size of bins is size of the ranges +1 */
+                        sta->tx_lat[i].bin_count =
+                                tx_latency->n_ranges + 1;
+                        sta->tx_lat[i].bins  = kcalloc(sta->tx_lat[i].bin_count,
+                                                       sizeof(u32),
+                                                       GFP_ATOMIC);
+                }
+
+        rcu_read_unlock();
+
         sta_dbg(sdata, "Allocated STA %pM\n", sta->sta.addr);
 
         return sta;