[PATCH net 1/1] net: stmmac: Resolve poor line rate after switching from TSO off to TSO on

Subsystems: networking drivers, stmmac ethernet driver, the rest

STALE1512d

3 messages, 2 authors, 2022-07-15 · open the first message on its own page

[PATCH net 1/1] net: stmmac: Resolve poor line rate after switching from TSO off to TSO on

From: Wong Vee Khee <hidden>
Date: 2022-02-28 11:13:49 

From: Ling Pei Lee <redacted>

Sequential execution of these steps:
i) TSO ON – iperf3 execution,
ii) TSO OFF – iperf3 execution,
iii) TSO ON – iperf3 execution, it leads to iperf3 0 bytes transfer.

Example of mentioned Issue happened:
root@TGLA:~# iperf3 -c 169.254.168.191
Connecting to host 169.254.168.191, port 5201
[  5] local 169.254.50.108 port 45846 connected to 169.254.168.191
port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec   113 MBytes   947 Mbits/sec    0    378 KBytes
[  5]   1.00-2.00   sec   111 MBytes   933 Mbits/sec    0    378 KBytes
[  5]   2.00-3.00   sec   111 MBytes   933 Mbits/sec    0    378 KBytes
[  5]   3.00-4.00   sec   111 MBytes   929 Mbits/sec    0    378 KBytes
[  5]   4.00-5.00   sec   111 MBytes   934 Mbits/sec    0    378 KBytes
[  5]   5.00-6.00   sec   111 MBytes   932 Mbits/sec    0    378 KBytes
[  5]   6.00-7.00   sec   111 MBytes   932 Mbits/sec    0    378 KBytes
[  5]   7.00-8.00   sec   111 MBytes   932 Mbits/sec    0    378 KBytes
[  5]   8.00-9.00   sec   111 MBytes   931 Mbits/sec    0    378 KBytes
[  5]   9.00-10.00  sec   111 MBytes   932 Mbits/sec    0    378 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  1.09 GBytes   933 Mbits/sec    0    sender
[  5]   0.00-10.00  sec  1.09 GBytes   932 Mbits/sec         receiver

iperf Done.
root@TGLA:~# ethtool -K enp0s30f4 tso off
root@TGLA:~# iperf3 -c 169.254.168.191
Connecting to host 169.254.168.191, port 5201
[  5] local 169.254.50.108 port 45854 connected to 169.254.168.191
port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec   104 MBytes   870 Mbits/sec    0    352 KBytes
[  5]   1.00-2.00   sec   101 MBytes   850 Mbits/sec    0    369 KBytes
[  5]   2.00-3.00   sec   102 MBytes   860 Mbits/sec    0    369 KBytes
[  5]   3.00-4.00   sec   102 MBytes   853 Mbits/sec    0    369 KBytes
[  5]   4.00-5.00   sec   102 MBytes   855 Mbits/sec    0    369 KBytes
[  5]   5.00-6.00   sec   101 MBytes   849 Mbits/sec    0    369 KBytes
[  5]   6.00-7.00   sec   102 MBytes   860 Mbits/sec    0    369 KBytes
[  5]   7.00-8.00   sec   102 MBytes   853 Mbits/sec    0    369 KBytes
[  5]   8.00-9.00   sec   101 MBytes   851 Mbits/sec    0    369 KBytes
[  5]   9.00-10.00  sec   102 MBytes   856 Mbits/sec    0    369 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  1020 MBytes   856 Mbits/sec    0    sender
[  5]   0.00-10.00  sec  1019 MBytes   854 Mbits/sec         receiver

iperf Done.
root@TGLA:~# ethtool -K enp0s30f4 tso on
root@TGLA:~# iperf3 -c 169.254.168.191
Connecting to host 169.254.168.191, port 5201
[  5] local 169.254.50.108 port 45860 connected to 169.254.168.191
port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec   107 KBytes   879 Kbits/sec    0   1.41 KBytes
[  5]   1.00-2.00   sec  0.00 Bytes  0.00 bits/sec    0   1.41 KBytes
[  5]   2.00-3.00   sec  0.00 Bytes  0.00 bits/sec    0   1.41 KBytes
[  5]   3.00-4.00   sec  0.00 Bytes  0.00 bits/sec    0   1.41 KBytes
[  5]   4.00-5.00   sec  0.00 Bytes  0.00 bits/sec    0   1.41 KBytes
[  5]   5.00-6.00   sec  0.00 Bytes  0.00 bits/sec    0   1.41 KBytes
[  5]   6.00-7.00   sec  0.00 Bytes  0.00 bits/sec    0   1.41 KBytes
[  5]   7.00-8.00   sec  0.00 Bytes  0.00 bits/sec    0   1.41 KBytes

Clear mss in TDES and call stmmac_enable_tso() to indicate
a new TSO transmission when it is enabled from TSO off using
ethtool command

Fixes: f748be531d70 ("stmmac: support new GMAC4")
Signed-off-by: Ling Pei Lee <redacted>
Signed-off-by: Wong Vee Khee <redacted>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index b745d624b2cb..9e2ea0e0bd68 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -5460,6 +5460,8 @@ static netdev_features_t stmmac_fix_features(struct net_device *dev,
 					     netdev_features_t features)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
+	u32 tx_cnt = priv->plat->tx_queues_to_use;
+	u32 chan;
 
 	if (priv->plat->rx_coe == STMMAC_RX_COE_NONE)
 		features &= ~NETIF_F_RXCSUM;
@@ -5483,6 +5485,16 @@ static netdev_features_t stmmac_fix_features(struct net_device *dev,
 			priv->tso = false;
 	}
 
+	for (chan = 0; chan < tx_cnt; chan++) {
+		struct stmmac_tx_queue *tx_q = &priv->tx_queue[chan];
+
+		/* TSO and TBS cannot co-exist */
+		if (tx_q->tbs & STMMAC_TBS_AVAIL)
+			continue;
+
+		tx_q->mss = 0;
+		stmmac_enable_tso(priv, priv->ioaddr, priv->tso, chan);
+	}
 	return features;
 }
 
-- 
2.25.1

Re: [PATCH net 1/1] net: stmmac: Resolve poor line rate after switching from TSO off to TSO on

From: Jakub Kicinski <kuba@kernel.org>
Date: 2022-03-03 06:32:54 

On Mon, 28 Feb 2022 19:15:58 +0800 Wong Vee Khee wrote:
From: Ling Pei Lee <redacted>

Sequential execution of these steps:
i) TSO ON – iperf3 execution,
ii) TSO OFF – iperf3 execution,
iii) TSO ON – iperf3 execution, it leads to iperf3 0 bytes transfer.
IMHO the iperf output can be dropped from the commit message, 
it doesn't add much beyond this description.

Clear mss in TDES and call stmmac_enable_tso() to indicate
a new TSO transmission when it is enabled from TSO off using
ethtool command
How does the TSO get disabled I don't see any ...enable_tso(, 0, )
calls in the driver? And why call enable in fix_features rather 
than set_features?

Re: [PATCH net 1/1] net: stmmac: Resolve poor line rate after switching from TSO off to TSO on

From: Wong Vee Khee <hidden>
Date: 2022-07-15 12:51:58 

On Wed, Mar 02, 2022 at 10:32:48PM -0800, Jakub Kicinski wrote:
On Mon, 28 Feb 2022 19:15:58 +0800 Wong Vee Khee wrote:
quoted
From: Ling Pei Lee <redacted>

Sequential execution of these steps:
i) TSO ON – iperf3 execution,
ii) TSO OFF – iperf3 execution,
iii) TSO ON – iperf3 execution, it leads to iperf3 0 bytes transfer.
IMHO the iperf output can be dropped from the commit message, 
it doesn't add much beyond this description.
Noted. Will drop those on next revision of pull request.
quoted
Clear mss in TDES and call stmmac_enable_tso() to indicate
a new TSO transmission when it is enabled from TSO off using
ethtool command
How does the TSO get disabled I don't see any ...enable_tso(, 0, )
calls in the driver? And why call enable in fix_features rather 
than set_features?
It is disable when 'priv->tso = 0' in this same function.
The reason I put this in fix_features rather than set_features is
because the commit f748be531d70("stmmac: support new GMAC4") has
already introduced the following codes in fix_features:-

+	/* Disable tso if asked by ethtool */
+	if ((priv->plat->tso_en) && (priv->dma_cap.tsoen)) {
+		if (features & NETIF_F_TSO)
+			priv->tso = true;
+		else
+			priv->tso = false;
+	}

BR,
 Vee Khee
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