Re: [Make-wifi-fast] [PATCH v6 4/4] ath10k: reporting estimated tx airtime for fairness

[Kan Yan <kyan@google.com>]

Hi Toke,

This patch looks good to me. Great job on getting the airtime fairness
scheduling framework done!


On Tue, Jan 22, 2019 at 6:21 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> From: Kan Yan <kyan@google.com>
>
> Transmit airtime will be estimated from last tx rate used.
> Firmware report tx rate by peer stats. Airtime is computed
> on tx path and the same will be reported to mac80211 upon
> tx completion.
>
> This change is based on Kan's orginal commit in Chromium tree
> ("CHROMIUM: ath10k: Implementing airtime fairness based TX scheduler")
> ref: https://chromium-review.googlesource.com/588190
>
> Tested on QCA4019 with firmware version 10.4-3.2.1.1-00015
> Tested on QCA9984 with firmware version 10.4-3.9.0.1-00005
>
> Signed-off-by: Kan Yan <kyan@google.com>
> [rmanohar@codeaurora.org: ported only the airtime computation]
> Signed-off-by: Rajkumar Manoharan <rmanohar@codeaurora.org>
> [toke@redhat.com: Rebase to mac80211-next, add test note]
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> ---
>
> Rajkumar / Kan: Please check that I didn't mess anything up while
> rebasing this onto the current mac80211-next branch!
>
>  drivers/net/wireless/ath/ath10k/core.h   |  2 +
>  drivers/net/wireless/ath/ath10k/htt_rx.c |  1 +
>  drivers/net/wireless/ath/ath10k/mac.c    | 57 ++++++++++++++++++++++--
>  drivers/net/wireless/ath/ath10k/txrx.c   |  4 ++
>  4 files changed, 61 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
> index 28cecf7375f8..4528a6e47b8d 100644
> --- a/drivers/net/wireless/ath/ath10k/core.h
> +++ b/drivers/net/wireless/ath/ath10k/core.h
> @@ -126,6 +126,7 @@ struct ath10k_skb_cb {
>         u8 flags;
>         u8 eid;
>         u16 msdu_id;
> +       u16 airtime_est;
>         struct ieee80211_vif *vif;
>         struct ieee80211_txq *txq;
>  } __packed;
> @@ -498,6 +499,7 @@ struct ath10k_sta {
>         u16 peer_id;
>         struct rate_info txrate;
>         struct ieee80211_tx_info tx_info;
> +       u32 last_tx_bitrate;
>
>         struct work_struct update_wk;
>         u64 rx_duration;
> diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c b/drivers/net/wireless/ath/ath10k/htt_rx.c
> index dc9895f2eb9d..6a93b57900ae 100644
> --- a/drivers/net/wireless/ath/ath10k/htt_rx.c
> +++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
> @@ -3078,6 +3078,7 @@ ath10k_update_per_peer_tx_stats(struct ath10k *ar,
>
>         arsta->txrate.nss = txrate.nss;
>         arsta->txrate.bw = ath10k_bw_to_mac80211_bw(txrate.bw);
> +       arsta->last_tx_bitrate = cfg80211_calculate_bitrate(&arsta->txrate);
>         if (sgi)
>                 arsta->txrate.flags |= RATE_INFO_FLAGS_SHORT_GI;
>
> diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
> index cf7fdf72e990..b13dcb4533cb 100644
> --- a/drivers/net/wireless/ath/ath10k/mac.c
> +++ b/drivers/net/wireless/ath/ath10k/mac.c
> @@ -3544,7 +3544,7 @@ static void ath10k_tx_h_add_p2p_noa_ie(struct ath10k *ar,
>  static void ath10k_mac_tx_h_fill_cb(struct ath10k *ar,
>                                     struct ieee80211_vif *vif,
>                                     struct ieee80211_txq *txq,
> -                                   struct sk_buff *skb)
> +                                   struct sk_buff *skb, u16 airtime)
>  {
>         struct ieee80211_hdr *hdr = (void *)skb->data;
>         struct ath10k_skb_cb *cb = ATH10K_SKB_CB(skb);
> @@ -3561,6 +3561,7 @@ static void ath10k_mac_tx_h_fill_cb(struct ath10k *ar,
>
>         cb->vif = vif;
>         cb->txq = txq;
> +       cb->airtime_est = airtime;
>  }
>
>  bool ath10k_mac_tx_frm_has_freq(struct ath10k *ar)
> @@ -3948,6 +3949,49 @@ static bool ath10k_mac_tx_can_push(struct ieee80211_hw *hw,
>         return false;
>  }
>
> +/* Return estimated airtime in microsecond, which is calculated using last
> + * reported TX rate. This is just a rough estimation because host driver has no
> + * knowledge of the actual transmit rate, retries or aggregation. If actual
> + * airtime can be reported by firmware, then delta between estimated and actual
> + * airtime can be adjusted from deficit.
> + */
> +#define IEEE80211_ATF_OVERHEAD         100     /* IFS + some slot time */
> +#define IEEE80211_ATF_OVERHEAD_IFS     16      /* IFS only */
> +static u16 ath10k_mac_update_airtime(struct ath10k *ar,
> +                                    struct ieee80211_txq *txq,
> +                                    struct sk_buff *skb)
> +{
> +       struct ath10k_sta *arsta;
> +       u32 pktlen;
> +       u16 airtime = 0;
> +
> +       if (!txq || !txq->sta)
> +               return airtime;
> +
> +       spin_lock_bh(&ar->data_lock);
> +       arsta = (struct ath10k_sta *)txq->sta->drv_priv;
> +
> +       pktlen = skb->len + 38; /* Assume MAC header 30, SNAP 8 for most case */
> +       if (arsta->last_tx_bitrate) {
> +               /* airtime in us, last_tx_bitrate in 100kbps */
> +               airtime = (pktlen * 8 * (1000 / 100))
> +                               / arsta->last_tx_bitrate;
> +               /* overhead for media access time and IFS */
> +               airtime += IEEE80211_ATF_OVERHEAD_IFS;
> +       } else {
> +               /* This is mostly for throttle excessive BC/MC frames, and the
> +                * airtime/rate doesn't need be exact. Airtime of BC/MC frames
> +                * in 2G get some discount, which helps prevent very low rate
> +                * frames from being blocked for too long.
> +                */
> +               airtime = (pktlen * 8 * (1000 / 100)) / 60; /* 6M */
> +               airtime += IEEE80211_ATF_OVERHEAD;
> +       }
> +       spin_unlock_bh(&ar->data_lock);
> +
> +       return airtime;
> +}
> +
>  int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
>                            struct ieee80211_txq *txq)
>  {
> @@ -3963,6 +4007,7 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
>         size_t skb_len;
>         bool is_mgmt, is_presp;
>         int ret;
> +       u16 airtime;
>
>         spin_lock_bh(&ar->htt.tx_lock);
>         ret = ath10k_htt_tx_inc_pending(htt);
> @@ -3980,7 +4025,8 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
>                 return -ENOENT;
>         }
>
> -       ath10k_mac_tx_h_fill_cb(ar, vif, txq, skb);
> +       airtime = ath10k_mac_update_airtime(ar, txq, skb);
> +       ath10k_mac_tx_h_fill_cb(ar, vif, txq, skb, airtime);
>
>         skb_len = skb->len;
>         txmode = ath10k_mac_tx_h_get_txmode(ar, vif, sta, skb);
> @@ -4247,8 +4293,10 @@ static void ath10k_mac_op_tx(struct ieee80211_hw *hw,
>         bool is_mgmt;
>         bool is_presp;
>         int ret;
> +       u16 airtime;
>
> -       ath10k_mac_tx_h_fill_cb(ar, vif, txq, skb);
> +       airtime = ath10k_mac_update_airtime(ar, txq, skb);
> +       ath10k_mac_tx_h_fill_cb(ar, vif, txq, skb, airtime);
>
>         txmode = ath10k_mac_tx_h_get_txmode(ar, vif, sta, skb);
>         txpath = ath10k_mac_tx_h_get_txpath(ar, skb, txmode);
> @@ -8603,6 +8651,9 @@ int ath10k_mac_register(struct ath10k *ar)
>                 wiphy_ext_feature_set(ar->hw->wiphy,
>                                       NL80211_EXT_FEATURE_ACK_SIGNAL_SUPPORT);
>
> +       if (ath10k_peer_stats_enabled(ar))
> +               wiphy_ext_feature_set(ar->hw->wiphy,
> +                                     NL80211_EXT_FEATURE_AIRTIME_FAIRNESS);
>         /*
>          * on LL hardware queues are managed entirely by the FW
>          * so we only advertise to mac we can do the queues thing
> diff --git a/drivers/net/wireless/ath/ath10k/txrx.c b/drivers/net/wireless/ath/ath10k/txrx.c
> index 23606b6972d0..8e7c416cd330 100644
> --- a/drivers/net/wireless/ath/ath10k/txrx.c
> +++ b/drivers/net/wireless/ath/ath10k/txrx.c
> @@ -95,6 +95,10 @@ int ath10k_txrx_tx_unref(struct ath10k_htt *htt,
>                 wake_up(&htt->empty_tx_wq);
>         spin_unlock_bh(&htt->tx_lock);
>
> +       if (txq && txq->sta)
> +               ieee80211_sta_register_airtime(txq->sta, txq->tid,
> +                                              skb_cb->airtime_est, 0);
> +
>         if (ar->dev_type != ATH10K_DEV_TYPE_HL)
>                 dma_unmap_single(dev, skb_cb->paddr, msdu->len, DMA_TO_DEVICE);
>
> --
> 2.20.1
>