Subject: Re: [PATCH] ath10k: remove iteration in wake_tx_queue
To:     =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= <toke@redhat.com>,
        kvalo@qca.qualcomm.com, linux-wireless@vger.kernel.org,
        ath10k@lists.infradead.org
Cc:     yiboz@codeaurora.org
References: <20190327162906.6010-1-erik.stromdahl@gmail.com>
 <87bm1qq92j.fsf@toke.dk>
From:   Erik Stromdahl <erik.stromdahl@gmail.com>
Message-ID: <8772dfe6-3f52-05ca-f55a-b7eae14fa7ac@gmail.com>
Date:   Tue, 16 Apr 2019 20:54:01 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.3.0
MIME-Version: 1.0
In-Reply-To: <87bm1qq92j.fsf@toke.dk>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk


On 4/1/19 1:05 PM, Toke Høiland-Jørgensen wrote:
> Erik Stromdahl <erik.stromdahl@gmail.com> writes:
> 
>> Iterating the TX queue and thereby dequeuing all available packets in the
>> queue could result in performance penalties on some SMP systems.
>>
>> The reason for this is most likely that the per-ac lock (active_txq_lock)
>> in mac80211 will be held by the CPU iterating the current queue.
>>
>> This will lock up other CPUs trying to push new messages on the TX
>> queue.
>>
>> Instead of iterating the queue we fetch just one packet at the time,
>> resulting in minimal starvation of the other CPUs.
> 
> Did you test this with Felix' patches reducing the time the lock is held
> in mac80211?
> 
> -Toke
> 
Hi Toke,

I am not aware of these patches. Can you please point them out for me?

--
Erik