From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]) by bombadil.infradead.org with esmtps (Exim 4.92.2 #3 (Red Hat Linux)) id 1iD032-0003U6-2u for ath10k@lists.infradead.org; Wed, 25 Sep 2019 05:41:09 +0000 MIME-Version: 1.0 Subject: Re: [PATCH] ath10k: remove iteration in wake_tx_queue From: Kalle Valo In-Reply-To: <20190327162906.6010-1-erik.stromdahl@gmail.com> References: <20190327162906.6010-1-erik.stromdahl@gmail.com> Message-Id: <20190925054107.A6456609F3@smtp.codeaurora.org> Date: Wed, 25 Sep 2019 05:41:07 +0000 (UTC) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "ath10k" Errors-To: ath10k-bounces+kvalo=adurom.com@lists.infradead.org To: Erik Stromdahl Cc: kvalo@qca.qualcomm.com, linux-wireless@vger.kernel.org, yiboz@codeaurora.org, ath10k@lists.infradead.org Erik Stromdahl wrote: > 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. > > Reported-by: Yibo Zhao > Signed-off-by: Erik Stromdahl Like others, I'm not convinced about this either. To me it looks like a quick workaround instead of properly investigating, and fixing, the root cause. To my understanding the throughput dip was caused by this commit: e3148cc5fecf ath10k: fix return value check in wake_tx_q op So to me it feels like the issue has been there all along, just hidden, and the fix above just exposed it. -- https://patchwork.kernel.org/patch/10873753/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches _______________________________________________ ath10k mailing list ath10k@lists.infradead.org http://lists.infradead.org/mailman/listinfo/ath10k