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Date:	Thu, 24 Mar 2016 17:53:17 +0530
From:	Mohammed Shafi Shajakhan <mohammed@...eaurora.org>
To:	Michal Kazior <michal.kazior@...to.com>
Cc:	linux-wireless <linux-wireless@...r.kernel.org>,
	Felix Fietkau <nbd@...nwrt.org>,
	Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
	Network Development <netdev@...r.kernel.org>,
	Dave Taht <dave.taht@...il.com>,
	"ath10k@...ts.infradead.org" <ath10k@...ts.infradead.org>,
	codel@...ts.bufferbloat.net, make-wifi-fast@...ts.bufferbloat.net,
	Johannes Berg <johannes@...solutions.net>,
	Tim Shepard <shep@...m.mit.edu>
Subject: Re: [RFCv2 2/3] ath10k: report per-station tx/rate rates to mac80211

On Thu, Mar 24, 2016 at 08:49:12AM +0100, Michal Kazior wrote:
> On 24 March 2016 at 08:19, Mohammed Shafi Shajakhan
> <mohammed@...eaurora.org> wrote:
> > Hi Michal,
> >
> > On Wed, Mar 16, 2016 at 11:17:57AM +0100, Michal Kazior wrote:
> >> The rate control is offloaded by firmware so it's
> >> challanging to provide expected throughput value
> >> for given station.
> >>
> >> This approach is naive as it reports last tx rate
> >> used for given station as provided by firmware
> >> stat event.
> >>
> >> This should be sufficient for airtime estimation
> >> used for fq-codel-in-mac80211 tx scheduling
> >> purposes now.
> >>
> >> This patch uses a very hacky way to get the stats.
> >> This is sufficient for proof-of-concept but must
> >> be cleaned up properly eventually.
> >>
> >> Signed-off-by: Michal Kazior <michal.kazior@...to.com>
> >> ---
> >>  drivers/net/wireless/ath/ath10k/core.h  |  5 +++
> >>  drivers/net/wireless/ath/ath10k/debug.c | 61 +++++++++++++++++++++++++++++----
> >>  drivers/net/wireless/ath/ath10k/mac.c   | 26 ++++++++------
> >>  drivers/net/wireless/ath/ath10k/wmi.h   |  2 +-
> >>  4 files changed, 76 insertions(+), 18 deletions(-)
> >>
> >> diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
> >> index 23ba03fb7a5f..3f76669d44cf 100644
> >> --- a/drivers/net/wireless/ath/ath10k/core.h
> >> +++ b/drivers/net/wireless/ath/ath10k/core.h
> >> @@ -331,6 +331,9 @@ struct ath10k_sta {
> >>       /* protected by conf_mutex */
> >>       bool aggr_mode;
> >>       u64 rx_duration;
> >> +
> >> +     u32 tx_rate_kbps;
> >> +     u32 rx_rate_kbps;
> >>  #endif
> >>  };
> >>
> >> @@ -372,6 +375,8 @@ struct ath10k_vif {
> >>       s8 def_wep_key_idx;
> >>
> >>       u16 tx_seq_no;
> >> +     u32 tx_rate_kbps;
> >> +     u32 rx_rate_kbps;
> >>
> >>       union {
> >>               struct {
> >> diff --git a/drivers/net/wireless/ath/ath10k/debug.c b/drivers/net/wireless/ath/ath10k/debug.c
> >> index 076d29b53ddf..cc7ebf04ae00 100644
> >> --- a/drivers/net/wireless/ath/ath10k/debug.c
> >> +++ b/drivers/net/wireless/ath/ath10k/debug.c
> >> @@ -316,6 +316,58 @@ static void ath10k_debug_fw_stats_reset(struct ath10k *ar)
> >>       spin_unlock_bh(&ar->data_lock);
> >>  }
> >>
> >> +static void ath10k_mac_update_txrx_rate_iter(void *data,
> >> +                                          u8 *mac,
> >> +                                          struct ieee80211_vif *vif)
> >> +{
> >> +     struct ath10k_fw_stats_peer *peer = data;
> >> +     struct ath10k_vif *arvif;
> >> +
> >> +     if (memcmp(vif->addr, peer->peer_macaddr, ETH_ALEN))
> >> +             return;
> >> +
> >> +     arvif = (void *)vif->drv_priv;
> >> +     arvif->tx_rate_kbps = peer->peer_tx_rate;
> >> +     arvif->rx_rate_kbps = peer->peer_rx_rate;
> >> +}
> >> +
> >> +static void ath10k_mac_update_txrx_rate(struct ath10k *ar,
> >> +                                     struct ath10k_fw_stats *stats)
> >> +{
> >> +     struct ieee80211_hw *hw = ar->hw;
> >> +     struct ath10k_fw_stats_peer *peer;
> >> +     struct ath10k_sta *arsta;
> >> +     struct ieee80211_sta *sta;
> >> +     const u8 *localaddr = NULL;
> >> +
> >> +     rcu_read_lock();
> >> +
> >> +     list_for_each_entry(peer, &stats->peers, list) {
> >> +             /* This doesn't account for multiple STA connected on different
> >> +              * vifs. Unfortunately there's no way to derive that from the available
> >> +              * information.
> >> +              */
> >> +             sta = ieee80211_find_sta_by_ifaddr(hw,
> >> +                                                peer->peer_macaddr,
> >> +                                                localaddr);
> >> +             if (!sta) {
> >> +                     /* This tries to update multicast rates */
> >> +                     ieee80211_iterate_active_interfaces_atomic(
> >> +                                     hw,
> >> +                                     IEEE80211_IFACE_ITER_NORMAL,
> >> +                                     ath10k_mac_update_txrx_rate_iter,
> >> +                                     peer);
> >> +                     continue;
> >> +             }
> >> +
> >> +             arsta = (void *)sta->drv_priv;
> >> +             arsta->tx_rate_kbps = peer->peer_tx_rate;
> >> +             arsta->rx_rate_kbps = peer->peer_rx_rate;
> >> +     }
> >> +
> >> +     rcu_read_unlock();
> >> +}
> >> +
> >>  void ath10k_debug_fw_stats_process(struct ath10k *ar, struct sk_buff *skb)
> >>  {
> >>       struct ath10k_fw_stats stats = {};
> >> @@ -335,6 +387,8 @@ void ath10k_debug_fw_stats_process(struct ath10k *ar, struct sk_buff *skb)
> >>               goto free;
> >>       }
> >>
> >> +     ath10k_mac_update_txrx_rate(ar, &stats);
> >> +
> >>       /* Stat data may exceed htc-wmi buffer limit. In such case firmware
> >>        * splits the stats data and delivers it in a ping-pong fashion of
> >>        * request cmd-update event.
> >> @@ -351,13 +405,6 @@ void ath10k_debug_fw_stats_process(struct ath10k *ar, struct sk_buff *skb)
> >>       if (peer_stats_svc)
> >>               ath10k_sta_update_rx_duration(ar, &stats.peers);
> >>
> >> -     if (ar->debug.fw_stats_done) {
> >> -             if (!peer_stats_svc)
> >> -                     ath10k_warn(ar, "received unsolicited stats update event\n");
> >> -
> >> -             goto free;
> >> -     }
> >> -
> >
> > [shafi] As you had suggested previously, should we completely clean up this ping
> > - pong response approach for f/w stats, (or) this should be retained to support
> > backward compatibility and also for supporting ping - pong response when user
> > cats for fw-stats (via debugfs) (i did see in the commit message this needs to
> > be cleaned up)
> 
> I think it makes sense to remove the ping-pong logic and rely on
> periodic updates alone, including fw_stats and ethstats handling.
> 
> 
> >> -     if (test_bit(WMI_SERVICE_PEER_STATS, ar->wmi.svc_map)) {
> >> -             param = ar->wmi.pdev_param->peer_stats_update_period;
> >> -             ret = ath10k_wmi_pdev_set_param(ar, param,
> >> -                                             PEER_DEFAULT_STATS_UPDATE_PERIOD);
> >> -             if (ret) {
> >> -                     ath10k_warn(ar,
> >> -                                 "failed to set peer stats period : %d\n",
> >> -                                 ret);
> >> -                     goto err_core_stop;
> >> -             }
> >> +     param = ar->wmi.pdev_param->peer_stats_update_period;
> >> +     ret = ath10k_wmi_pdev_set_param(ar, param,
> >> +                                     PEER_DEFAULT_STATS_UPDATE_PERIOD);
> >> +     if (ret) {
> >> +             ath10k_warn(ar,
> >> +                         "failed to set peer stats period : %d\n",
> >> +                         ret);
> >> +             goto err_core_stop;
> >>       }
> >
> > [shafi] If i am correct this change requires 'PEER_STATS' to be enabled by
> > default.
> 
> No, it does not. Periodic stats have been available since forever.

[shafi] Michal, sorry i was talking about enabling WMI_PEER_STATS feature for
10.2, and we have a patch pushed recently to reduce the number of peers if
'WMI_PEER_STATS' feature is enabled(avoiding f/w crash due to memory
constraints) . But this patch requires the feature to be
turned ON always (with periodic stats update as well for evey 100ms). Please
correct me if my understanding is wrong.

> 
> 
> >> diff --git a/drivers/net/wireless/ath/ath10k/wmi.h b/drivers/net/wireless/ath/ath10k/wmi.h
> >> index 4d3cbc44fcd2..2877a3a27b95 100644
> >> --- a/drivers/net/wireless/ath/ath10k/wmi.h
> >> +++ b/drivers/net/wireless/ath/ath10k/wmi.h
> >> @@ -3296,7 +3296,7 @@ struct wmi_csa_event {
> >>  /* the definition of different PDEV parameters */
> >>  #define PDEV_DEFAULT_STATS_UPDATE_PERIOD    500
> >>  #define VDEV_DEFAULT_STATS_UPDATE_PERIOD    500
> >> -#define PEER_DEFAULT_STATS_UPDATE_PERIOD    500
> >> +#define PEER_DEFAULT_STATS_UPDATE_PERIOD    100
> >
> > [shafi] Is this for more granularity since 500ms is not sufficient ?, I understand
> > the firmware has default stats_update_period as 500ms and i hope it supports
> > 100ms as well, Also if we are going to support period stats update we may need to
> > accumulate the information in driver (like this change and rx_duration
> 
> The patch is used for rough rate estimation which is used to keep Tx
> queues filled only with 1-2 txops worth of data. Signal conditions can
> change vastly so I figured I need the peer stat update events come
> more often. I didn't really verify if they come every 100ms. The patch
> already served it's job as a proof-of-concept for smarter tx queuing.

[shafi] Ok, sure. I understand very soon we will get this in ath10k as well
(though it is a POC) 
 
> 
> > I will try to take this change, rebase it to TOT and see how it goes.
> 
> There's really no benefit it taking this patch as a basis for periodic
> stat handling. Majority of this patch is just handling peer_tx_rate
> for rate estimation purposes. Feel free to knock yourself out with
> ripping out the ping-pong stat stuff though :)
>
[shafi] sure Michal, thanks !

regards,
shafi

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