From: Ben Greear <greearb@xxxxxxxxxxxxxxx>
The sta_info hash is designed to deal with an AP
with lots of stations associated, or a station interface
connected to a single AP.
However, when you have lots of station VIFs connected
to the same AP, the sta_info hash becomes worthless
as there is a single hash bucket that contains all the
entries in a linked list.
So, have the sdata object cache one of its station
interfaces. If we are a station VIF with a single
sta_info, then this means we can ignore the sta_info
hash entirely.
On a test case with 128 stations and 50 TCP streams,
tx performance went from around 80Mbps to 124Mbps.
Signed-off-by: Ben Greear <greearb@xxxxxxxxxxxxxxx>
---
v4: Use rcu_dereference_protected as designed, passing a mutex
as the second argument instead of hard-coding it to 1.
:100644 100644 a618bda... a7e7f5d... M net/mac80211/cfg.c
:100644 100644 493e2e8... c6386c7... M net/mac80211/ieee80211_i.h
:100644 100644 415f9c6... d87a76d... M net/mac80211/sta_info.c
net/mac80211/cfg.c | 6 ++++++
net/mac80211/ieee80211_i.h | 6 ++++++
net/mac80211/sta_info.c | 23 ++++++++++++++++++++++-
3 files changed, 34 insertions(+), 1 deletions(-)
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index a618bda..a7e7f5d 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1287,6 +1287,7 @@ static int ieee80211_change_station(struct wiphy *wiphy,
if (params->vlan && params->vlan != sta->sdata->dev) {
bool prev_4addr = false;
bool new_4addr = false;
+ struct sta_info *some_sta;
vlansdata = IEEE80211_DEV_TO_SUB_IF(params->vlan);
@@ -1312,7 +1313,12 @@ static int ieee80211_change_station(struct wiphy *wiphy,
prev_4addr = true;
}
+ some_sta = rcu_dereference_protected(sta->sdata->some_sta,
+ lockdep_is_held(&local->sta_mtx));
+ if (some_sta == sta)
+ rcu_assign_pointer(sta->sdata->some_sta, NULL);
sta->sdata = vlansdata;
+ rcu_assign_pointer(sta->sdata->some_sta, sta);
if (sta->sta_state == IEEE80211_STA_AUTHORIZED &&
prev_4addr != new_4addr) {
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 493e2e8..c6386c7 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -669,6 +669,12 @@ struct ieee80211_sub_if_data {
/* count for keys needing tailroom space allocation */
int crypto_tx_tailroom_needed_cnt;
+ /* A pointer to some station associated with this interface, or
+ * NULL. This allows opportunistic lookup for sta_info objects when
+ * sdata is a station with a single sta_info.
+ */
+ struct sta_info __rcu *some_sta;
+
struct net_device *dev;
struct ieee80211_local *local;
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 415f9c6..d87a76d 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -67,7 +67,12 @@
static int sta_info_hash_del(struct ieee80211_local *local,
struct sta_info *sta)
{
- struct sta_info *s;
+ struct sta_info *s, *some_sta;
+
+ some_sta = rcu_dereference_protected(sta->sdata->some_sta,
+ lockdep_is_held(&local->sta_mtx));
+ if (some_sta == sta)
+ rcu_assign_pointer(sta->sdata->some_sta, NULL);
s = rcu_dereference_protected(local->sta_hash[STA_HASH(sta->sta.addr)],
lockdep_is_held(&local->sta_mtx));
@@ -195,6 +200,20 @@ struct sta_info *sta_info_get(struct ieee80211_sub_if_data *sdata,
struct ieee80211_local *local = sdata->local;
struct sta_info *sta;
+ if (sdata->vif.type == NL80211_IFTYPE_STATION) {
+ struct sta_info *some_sta;
+
+ /* Shortcut for finding station entries for STATION VIFs */
+ some_sta = rcu_dereference(sdata->some_sta);
+ if (some_sta) {
+ if (WARN_ON(some_sta->sdata != sdata))
+ rcu_assign_pointer(sdata->some_sta, NULL);
+ else
+ if (ether_addr_equal(some_sta->sta.addr, addr))
+ return some_sta;
+ }
+ }
+
sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
lockdep_is_held(&local->sta_mtx));
while (sta) {
@@ -278,6 +297,8 @@ static void sta_info_hash_add(struct ieee80211_local *local,
lockdep_assert_held(&local->sta_mtx);
sta->hnext = local->sta_hash[STA_HASH(sta->sta.addr)];
rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)], sta);
+
+ rcu_assign_pointer(sta->sdata->some_sta, sta);
}
static void sta_unblock(struct work_struct *wk)
--
1.7.3.4
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