[ath9k-devel] Retry control & iwconfig

[Olivier Marce <Olivier.Marce@alcatel-lucent.com>]

Hi Pradeep,
thanks, this helped me a lot.
It pointed me out to iw command "set noack_map" that is made to set 
IEEE80211_TX_CTL_NO_ACK flag, and that I did not consider before.

I then used "iw <dev> set noack_map 9" to avoid waiting for ACK  and to 
avoid retries by <dev>.
What I expected was to see almost no difference with noack when the link 
conditions are good (i.e. high RSSI level).
But this is not the case, with noack set, the data transfer is almost 
not possible (I used iperf, and it even does not complete its test, 95 
to 98% lost packet with ping).

What is the reason for this ? Does the NO_ACK bit has an additional 
impact on the device behaviour like not respecting the requested delays 
on the air, or whatever ?
Any idea ?

Thanks.

Olivier.

On 27/03/2014 05:20, Pradeep Reddy wrote:
> Hi Marc,
>
> You can set NO_ACK bit in Tx descriptor of each packet to indicate the
> hardware to not to wait for ACK, which in turn avoids retries for that
> particular packet.
>
> If you set IEEE80211_TX_CTL_NO_ACK flag in tx_ctl information, ath9k
> layer will take care of setting the Tx descriptor flag ATH9K_TXDESC_NOACK.
>
> Regards
> Pradeep
>
>
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-- 
Olivier Marc?
Alcatel-Lucent Bell Labs France