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Date:   Tue, 07 May 2019 19:14:53 +0800
From:   leiwa@codeaurora.org
To:     =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
Cc:     ath10k@lists.infradead.org, linux-wireless@vger.kernel.org
Subject: Re: [PATCH v2] ath10k: fix different tx duration output
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On 2019-04-18 16:07, Toke Høiland-Jørgensen wrote:
> leiwa@codeaurora.org writes:
> 
>> On 2019-04-17 17:26, Toke Høiland-Jørgensen wrote:
>>> Lei Wang <leiwa@codeaurora.org> writes:
>>> 
>>>> TX duration output of tx_stats in debugfs and station dump had big
>>>> difference because they got tx duration value from different 
>>>> statistic
>>>> data. We should use the same statistic data.
>>> 
>>> So are you sure you picked the most accurate one of the two? :)
>>> 
>>> -Toke
>> 
>> Hi Toke,
>> 
>> Yes.
>> Now for ath10k, there are two ways to get tx duration output.
>> One is got from tx_stats in debugfs reported by firmware. It is a 
>> total
>> value including all the frames which created by host and firmware sent
>> to the peer.
>> And the second is calculated from
>> ath10k_htt_rx_tx_compl_ind()-->ieee80211_sta_register_airtime(), here
>> the tx duration just includes the data frames sent from host to the
>> peer.
> 
> So the difference is that the former includes control frames as well? 
> Is
> that the only difference? And what exactly is a "big difference" (from
> the commit message)?
> 
Yes,it adds the duration time of receiving ACK frames.
 From my test,TX from AP to station with iperf UDP test in 
10s,tx_stats->tx_duration:5496623us,
and another value is 3934327us.
>> So the first value is preferable for station dump.
> 
> Hmm, I'm not sure if I agree with this. I specifically added the
> tx_duration to the station dump to be able to get the values used by 
> the
> airtime scheduler. This breaks with this patch.
> 
> -Toke
 From our internal discussing, we will revert this change.
Thanks.

Lei