[Make-wifi-fast] [PATCH RFC v4 3/4] mac80211: Add airtime accounting and scheduling to TXQs

Rajkumar Manoharan rmanohar at codeaurora.org
Fri Sep 28 05:27:41 EDT 2018

On 2018-09-28 00:51, Toke Høiland-Jørgensen wrote:
> On 28 September 2018 07:29:03 CEST, Rajkumar Manoharan
> <rmanohar at codeaurora.org> wrote:
>> On 2018-09-26 17:09, Rajkumar Manoharan wrote:
>>> On 2018-09-26 02:22, Toke Høiland-Jørgensen wrote:
>>>> Rajkumar Manoharan <rmanohar at codeaurora.org> writes:
>>> :( Yeah... I got confused with attached soft lockup in ARM platform.
>> Toke,
>> Cause for the soft lockup exposed in multi client scenario is due to
>> mixed order of fq_lock and active_txqs_lock. In wake_tx_queue or
>> push_pending
>> case, driver acquires active_txq_lock first by schedule_start and
>> followed by
>> fq_lock in tx_dequeue. The same order should be maintained in sta
>> cleanup.
>> Below change fixed the issue.
> Ah, great find! I'll fold this into the next version, thanks!

One more thing. As I mentioned earlier, scheduling wake_txqs_tasklet
is heavy load and causing random rcu stall issue. Hence I added
another API to schedule throttled txqs once for all. Also I did
a cleanup in kick_airtime by traversing list only once. With these
changes I don't see rcu stall issue. Please review and fold them as 


single_iter - clean up kick_airtime
sched_throttle - new API and separate tasklet for throttled txqs
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