No reorder buffer?

Adrian Chadd adrian at freebsd.org
Thu Jun 26 00:38:09 PDT 2014


... hm. Well, in normal operation the firmware is supposed to be doing
reordering. But I don't think ath10k runs the MAC in normal ethernet
pipe mode, right? So a lot of the firmware / hardware offload bits
don't work.

Can someone verify for me which mode the MAC is in? I forget what was done.



-a


On 24 June 2014 07:47, Denton Gentry <denton.gentry at gmail.com> wrote:
> I'm bridging ath10k to Ethernet, gathering pcaps on another ath10k
> system in monitor mode and on the Ethernet system which is receiving
> the packets. I see packets being delivered out of order to the
> Ethernet system. So far as I can tell, any packet which has to be
> re-sent on the Wifi link will be delivered out of order to Ethernet.
>
> I believe this happens because there is no reorder buffer.
> ieee80211_rx_reorder_ampdu returns because tid_agg_rx[tid] is NULL.
>
> I believe there is no reorder buffer because
> ieee80211_process_addba_request is not being called.
> ieee80211_process_addba_request would allocate tid_agg_rx[tid].
>
> I believe ieee80211_process_addba_request is not being called because
> the firmware processes the AddBA and does not pass it up. This is the
> part I am least sure about.
>
>
> Can anyone confirm or deny that this is correct: does the firmware
> process the AddBA, but not have a reorder buffer in the firmware?
>
>
> This is noticeable mostly because of Windows. The Windows TCP stack
> seems to react more strongly to packet reordering (inferred via SACKs,
> I guess), and slows down.
>
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