[RFC PATCH v4 2/3] mac80211: add periodic monitor for channel busy time

Baligh Gasmi
2022-06-01T11:31:46Z

Add a worker scheduled periodicaly to calculate the busy time average of
the current channel.

This will be used in the estimation for expected throughput.

Signed-off-by: Baligh Gasmi <gasmibal@gmail.com>
---
net/mac80211/ieee80211_i.h | 6 ++++
net/mac80211/iface.c | 65 ++++++++++++++++++++++++++++++++++++++
2 files changed, 71 insertions(+)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 86ef0a46a68c..2cb388335ce8 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -901,6 +901,7 @@ struct ieee80211_if_nan {
struct idr function_inst_ids;
};

+DECLARE_EWMA(avg_busy, 8, 4)
struct ieee80211_sub_if_data {
struct list_head list;

@@ -1024,6 +1025,11 @@ struct ieee80211_sub_if_data {
} debugfs;
#endif

+ struct delayed_work monitor_work;
+ u64 last_time;
+ u64 last_time_busy;
+ struct ewma_avg_busy avg_busy;
+
/* must be last, dynamically sized area in this! */
struct ieee80211_vif vif;
};
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 41531478437c..45b860c59d79 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1970,6 +1970,64 @@ static void ieee80211_assign_perm_addr(struct ieee80211_local *local,
mutex_unlock(&local->iflist_mtx);
}

+#define DEFAULT_MONITOR_INTERVAL_MS 1000
+
+static void ieee80211_if_monitor_work(struct work_struct *work)
+{
+ struct delayed_work *delayed_work = to_delayed_work(work);
+ struct ieee80211_sub_if_data *sdata =
+ container_of(delayed_work, struct ieee80211_sub_if_data,
+ monitor_work);
+ struct survey_info survey;
+ struct ieee80211_local *local = sdata->local;
+ struct ieee80211_chanctx_conf *chanctx_conf;
+ struct ieee80211_channel *channel = NULL;
+ int q = 0;
+ u64 interval = DEFAULT_MONITOR_INTERVAL_MS;
+
+ rcu_read_lock();
+ chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
+ if (chanctx_conf)
+ channel = chanctx_conf->def.chan;
+ rcu_read_unlock();
+
+ if (!channel)
+ goto end;
+
+ if (!local->started)
+ goto end;
+
+ do {
+ survey.filled = 0;
+ if (drv_get_survey(local, q++, &survey) != 0) {
+ survey.filled = 0;
+ break;
+ }
+ } while (channel != survey.channel);
+
+ if (survey.filled & SURVEY_INFO_TIME) {
+ /* real interval */
+ interval = survey.time - sdata->last_time;
+ /* store last time */
+ sdata->last_time = survey.time;
+ }
+
+ if (survey.filled & SURVEY_INFO_TIME_BUSY) {
+ /* busy */
+ u64 busy = survey.time_busy < sdata->last_time_busy ? 0 :
+ survey.time_busy - sdata->last_time_busy;
+ /* average percent busy time */
+ ewma_avg_busy_add(&sdata->avg_busy,
+ (busy * 100) / interval);
+ /* store last busy time */
+ sdata->last_time_busy = survey.time_busy;
+ }
+
+end:
+ schedule_delayed_work(&sdata->monitor_work,
+ msecs_to_jiffies(DEFAULT_MONITOR_INTERVAL_MS));
+}
+
int ieee80211_if_add(struct ieee80211_local *local, const char *name,
unsigned char name_assign_type,
struct wireless_dev **new_wdev, enum nl80211_iftype type,
@@ -2083,6 +2141,8 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
ieee80211_dfs_cac_timer_work);
INIT_DELAYED_WORK(&sdata->dec_tailroom_needed_wk,
ieee80211_delayed_tailroom_dec);
+ INIT_DELAYED_WORK(&sdata->monitor_work,
+ ieee80211_if_monitor_work);

for (i = 0; i < NUM_NL80211_BANDS; i++) {
struct ieee80211_supported_band *sband;
@@ -2154,6 +2214,9 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
list_add_tail_rcu(&sdata->list, &local->interfaces);
mutex_unlock(&local->iflist_mtx);

+ schedule_delayed_work(&sdata->monitor_work,
+ msecs_to_jiffies(DEFAULT_MONITOR_INTERVAL_MS));
+
if (new_wdev)
*new_wdev = &sdata->wdev;

@@ -2164,6 +2227,8 @@ void ieee80211_if_remove(struct ieee80211_sub_if_data *sdata)
{
ASSERT_RTNL();

+ cancel_delayed_work_sync(&sdata->monitor_work);
+
mutex_lock(&sdata->local->iflist_mtx);
list_del_rcu(&sdata->list);
mutex_unlock(&sdata->local->iflist_mtx);
--
2.36.1