linux-kernel - [PATCH 4.8 054/125] ath10k: fix throughput regression in multi client mode

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Date:   Sat, 29 Oct 2016 09:49:32 -0400
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Rajkumar Manoharan <rmanohar@....qualcomm.com>,
        Kalle Valo <kvalo@....qualcomm.com>
Subject: [PATCH 4.8 054/125] ath10k: fix throughput regression in multi client mode

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Rajkumar Manoharan <rmanohar@....qualcomm.com>

commit 18f53fe0f30331e826b075709ed7b26b9283235e upstream.

commit 7a0adc83f34d ("ath10k: improve tx scheduling") is causing
severe throughput drop in multi client mode. This issue is originally
reported in veriwave setup with 50 clients with TCP downlink traffic.
While increasing number of clients, the average throughput drops
gradually. With 50 clients, the combined peak throughput is decreased
to 98 Mbps whereas reverting given commit restored it to 550 Mbps.

Processing txqs for every tx completion is causing overhead. Ideally for
management frame tx completion, pending txqs processing can be avoided.
The change partly reverts the commit "ath10k: improve tx scheduling".
Processing pending txqs after all skbs tx completion will yeild enough
room to burst tx frames.

Fixes: 7a0adc83f34d ("ath10k: improve tx scheduling")
Signed-off-by: Rajkumar Manoharan <rmanohar@....qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@....qualcomm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/ath/ath10k/htt_rx.c |    2 ++
 drivers/net/wireless/ath/ath10k/txrx.c   |    2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/wireless/ath/ath10k/htt_rx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
@@ -2394,6 +2394,8 @@ static void ath10k_htt_txrx_compl_task(u
 	skb_queue_splice_init(&htt->rx_in_ord_compl_q, &rx_ind_q);
 	spin_unlock_irqrestore(&htt->rx_in_ord_compl_q.lock, flags);

+	ath10k_mac_tx_push_pending(ar);
+
 	spin_lock_irqsave(&htt->tx_fetch_ind_q.lock, flags);
 	skb_queue_splice_init(&htt->tx_fetch_ind_q, &tx_ind_q);
 	spin_unlock_irqrestore(&htt->tx_fetch_ind_q.lock, flags);
--- a/drivers/net/wireless/ath/ath10k/txrx.c
+++ b/drivers/net/wireless/ath/ath10k/txrx.c
@@ -119,8 +119,6 @@ int ath10k_txrx_tx_unref(struct ath10k_h
 	ieee80211_tx_status(htt->ar->hw, msdu);
 	/* we do not own the msdu anymore */

-	ath10k_mac_tx_push_pending(ar);
-
 	return 0;
 }