Sebastian Moeller <moeller0@xxxxxx> writes:
>> On Oct 17, 2019, at 11:44, Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote:
>>
>> Kan Yan <kyan@xxxxxxxxxx> writes:
>>
>>> Hi Toke,
>>>
>>> Thanks for getting this done! I will give it a try in the next few
>>> days. A few comments:
>>>
>>>> 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.
>>>
>>> Looks like ath10k driver zero out the info->status before calling
>>> ieee80211_tx_status(...):
>>> int ath10k_txrx_tx_unref(struct ath10k_htt *htt,
>>> const struct htt_tx_done *tx_done)
>>> {
>>> ...
>>> info = IEEE80211_SKB_CB(msdu);
>>> memset(&info->status, 0, sizeof(info->status));
>>> ...
>>> ieee80211_tx_status(htt->ar->hw, msdu);
>>> }
>>
>> Ah, bugger; I was afraid we'd run into this. A quick grep indicates that
>> it's only ath10k and iwl that do this, though, so it's probably
>> manageable to just fix this. I think the simplest solution is just to
>> restore the field after clearing, no?
>>
>>> We need either restore the info->status.tx_time_est or calling
>>> ieee80211_sta_update_pending_airtime() in ath10k before tx_time_est
>>> get erased.
>>>
>>>> + if (local->airtime_flags & AIRTIME_USE_AQL) {
>>>> + airtime = ieee80211_calc_expected_tx_airtime(hw, vif, txq->sta,
>>>> + skb->len + 38);
>>>
>>> I think it is better to put the "+ 38" that takes care of the header
>>> overhead inside ieee80211_calc_expected_tx_airtime().
>>
>> Hmm, no strong opinion about this; but yeah, since we have a dedicated
>> function for this use I guess there's no harm in adding it there :)
>>
>
> Silly question, is this Overhead guaranteed to be 38 Bytes for all
> eternity? Otherwise a variable or a preprocessor constant might be
> more future proof?
Well, yeah, as long as we're sending Ethernet packets. Which is kinda
baked into the WiFi standard :)
-Toke
