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[85.204.121.218]) by smtp.gmail.com with ESMTPSA id h3sm5459652ljf.12.2019.10.19.04.37.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Oct 2019 04:37:19 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id BD12A1804C8; Sat, 19 Oct 2019 13:37:18 +0200 (CEST) Subject: [PATCH v4 4/4] mac80211: Use Airtime-based Queue Limits (AQL) on packet dequeue From: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= To: Johannes Berg Cc: linux-wireless@vger.kernel.org, make-wifi-fast@lists.bufferbloat.net, ath10k@lists.infradead.org, John Crispin , Lorenzo Bianconi , Felix Fietkau , Kan Yan , Rajkumar Manoharan , Kevin Hayes Date: Sat, 19 Oct 2019 13:37:18 +0200 Message-ID: <157148503865.2989444.7118792679603045723.stgit@toke.dk> In-Reply-To: <157148503415.2989444.7391437309981941226.stgit@toke.dk> References: <157148503415.2989444.7391437309981941226.stgit@toke.dk> User-Agent: StGit/0.20 MIME-Version: 1.0 X-MC-Unique: BjThIq7eM0Gx-bXcFrpW7Q-1 X-Mimecast-Spam-Score: 0 Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org From: Toke Høiland-Jørgensen The previous commit added the ability to throttle stations when they queue too much airtime in the hardware. This commit enables the functionality by calculating the expected airtime usage of each packet that is dequeued from the TXQs in mac80211, and accounting that as pending airtime. The estimated airtime for each skb is stored in the tx_info, so we can subtract the same amount from the running total when the skb is freed or recycled. The throttling mechanism relies on this accounting to be accurate (i.e., that we are not freeing skbs without subtracting any airtime they were accounted for), so we put the subtraction into ieee80211_report_used_skb(). As an optimisation, we also subtract the airtime on regular TX completion, zeroing out the value stored in the packet afterwards, to avoid having to do an expensive lookup of the station from the packet data on every packet. This patch does *not* include any mechanism to wake a throttled TXQ again, on the assumption that this will happen anyway as a side effect of whatever freed the skb (most commonly a TX completion). Signed-off-by: Toke Høiland-Jørgensen --- net/mac80211/status.c | 38 ++++++++++++++++++++++++++++++++++++++ net/mac80211/tx.c | 21 +++++++++++++++++++++ 2 files changed, 59 insertions(+) diff --git a/net/mac80211/status.c b/net/mac80211/status.c index ab8ba5835ca0..905b4afd457d 100644 --- a/net/mac80211/status.c +++ b/net/mac80211/status.c @@ -676,6 +676,33 @@ static void ieee80211_report_used_skb(struct ieee80211_local *local, if (dropped) acked = false; + if (info->tx_time_est) { + struct ieee80211_sub_if_data *sdata; + struct sta_info *sta = NULL; + u8 *qc, ac; + int tid; + + rcu_read_lock(); + + sdata = ieee80211_sdata_from_skb(local, skb); + if (sdata) + sta = sta_info_get_bss(sdata, skb_mac_header(skb)); + + if (ieee80211_is_data_qos(hdr->frame_control)) { + qc = ieee80211_get_qos_ctl(hdr); + tid = qc[0] & 0xf; + ac = ieee80211_ac_from_tid(tid); + } else { + ac = IEEE80211_AC_BE; + } + + ieee80211_sta_update_pending_airtime(local, sta, ac, + info->tx_time_est << 2, + true); + rcu_read_unlock(); + + } + if (info->flags & IEEE80211_TX_INTFL_MLME_CONN_TX) { struct ieee80211_sub_if_data *sdata; @@ -930,6 +957,17 @@ static void __ieee80211_tx_status(struct ieee80211_hw *hw, tid = qc[0] & 0xf; } + if (info->tx_time_est) { + /* Do this here to avoid the expensive lookup of the sta + * in ieee80211_report_used_skb(). + */ + ieee80211_sta_update_pending_airtime(local, sta, + ieee80211_ac_from_tid(tid), + info->tx_time_est << 2, + true); + info->tx_time_est = 0; + } + if (!acked && ieee80211_is_back_req(fc)) { u16 control; diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 12653d873b8c..b8ff56d1d661 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -3542,6 +3542,9 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw, WARN_ON_ONCE(softirq_count() == 0); + if (!ieee80211_txq_airtime_check(hw, txq)) + return NULL; + begin: spin_lock_bh(&fq->lock); @@ -3652,6 +3655,24 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw, } IEEE80211_SKB_CB(skb)->control.vif = vif; + + if (local->airtime_flags & AIRTIME_USE_AQL) { + u32 airtime; + + airtime = ieee80211_calc_expected_tx_airtime(hw, vif, txq->sta, + skb->len); + if (airtime) { + /* We only have 10 bits in tx_time_est, so store airtime + * in increments of 4 us and clamp the maximum to 2**12-1 + */ + airtime = min_t(u32, airtime, 4095) & ~3U; + info->tx_time_est = airtime >> 2; + ieee80211_sta_update_pending_airtime(local, tx.sta, + txq->ac, airtime, + false); + } + } + return skb; out: