linux-kernel - [PATCH] net: atlantic: make RX page order tunable via module param

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Message-ID: <tencent_E71C2F71D9631843941A5DF87204D1B5B509@qq.com>
Date: Sat,  6 Sep 2025 21:54:34 +0800
From: Yangyu Chen <cyy@...self.name>
To: netdev@...r.kernel.org
Cc: Igor Russkikh <irusskikh@...vell.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	linux-kernel@...r.kernel.org,
	Yangyu Chen <cyy@...self.name>
Subject: [PATCH] net: atlantic: make RX page order tunable via module param

On systems like AMD Strix Halo with Thunderbolt, RX map/unmap operations
with IOMMU introduce significant performance overhead, making it difficult
to achieve line rate with 10G NICs even with TCP over MTU 1500. Using
higher order pages reduces this overhead, so this parameter is now
configurable.

After applying this patch and setting `rxpageorder=3`, testing with QNAP
QNA-T310G1S on 10G Ethernet (MTU 1500) using `iperf3 -R` on IPv6 achieved
9.28Gbps compared to only 2.26Gbps previously.

Signed-off-by: Yangyu Chen <cyy@...self.name>
---
Should we also consider make default AQ_CFG_RX_PAGEORDER to 3?

Test result showing performance improvement:
$ sudo insmod drivers/net/ethernet/aquantia/atlantic/atlantic.ko
$ sudo ip link set enp99s0 up
$ iperf3 -c fe80::3a63:bbff:fe2e:1a68%enp99s0 -R
Connecting to host fe80::3a63:bbff:fe2e:1a68%enp99s0, port 5201
Reverse mode, remote host fe80::3a63:bbff:fe2e:1a68%enp99s0 is sending
[  5] local fe80::265e:beff:fe6a:4da1 port 39588 connected to fe80::3a63:bbff:fe2e:1a68 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec   271 MBytes  2.27 Gbits/sec                  
[  5]   1.00-2.00   sec   270 MBytes  2.27 Gbits/sec                  
[  5]   2.00-3.00   sec   268 MBytes  2.25 Gbits/sec                  
[  5]   3.00-4.00   sec   270 MBytes  2.26 Gbits/sec                  
[  5]   4.00-5.00   sec   268 MBytes  2.25 Gbits/sec                  
[  5]   5.00-6.00   sec   269 MBytes  2.26 Gbits/sec                  
[  5]   6.00-7.00   sec   268 MBytes  2.25 Gbits/sec                  
[  5]   7.00-8.00   sec   268 MBytes  2.25 Gbits/sec                  
[  5]   8.00-9.00   sec   268 MBytes  2.25 Gbits/sec                  
[  5]   9.00-10.00  sec   268 MBytes  2.25 Gbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  2.63 GBytes  2.26 Gbits/sec    1            sender
[  5]   0.00-10.00  sec  2.63 GBytes  2.26 Gbits/sec                  receiver

iperf Done.
$ sudo rmmod atlantic
$ sudo insmod drivers/net/ethernet/aquantia/atlantic/atlantic.ko rxpageorder=3
$ sudo ip link set enp99s0 up
$ iperf3 -c fe80::3a63:bbff:fe2e:1a68%enp99s0 -R
Connecting to host fe80::3a63:bbff:fe2e:1a68%enp99s0, port 5201
Reverse mode, remote host fe80::3a63:bbff:fe2e:1a68%enp99s0 is sending
[  5] local fe80::265e:beff:fe6a:4da1 port 43356 connected to fe80::3a63:bbff:fe2e:1a68 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  1.08 GBytes  9.28 Gbits/sec                  
[  5]   1.00-2.00   sec  1.08 GBytes  9.28 Gbits/sec                  
[  5]   2.00-3.00   sec  1.08 GBytes  9.28 Gbits/sec                  
[  5]   3.00-4.00   sec  1.08 GBytes  9.28 Gbits/sec                  
[  5]   4.00-5.00   sec  1.08 GBytes  9.28 Gbits/sec                  
[  5]   5.00-6.00   sec  1.08 GBytes  9.28 Gbits/sec                  
[  5]   6.00-7.00   sec  1.08 GBytes  9.28 Gbits/sec                  
[  5]   7.00-8.00   sec  1.08 GBytes  9.28 Gbits/sec                  
[  5]   8.00-9.00   sec  1.08 GBytes  9.28 Gbits/sec                  
[  5]   9.00-10.00  sec  1.08 GBytes  9.28 Gbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  10.8 GBytes  9.28 Gbits/sec    0            sender
[  5]   0.00-10.00  sec  10.8 GBytes  9.28 Gbits/sec                  receiver

iperf Done.
---
 drivers/net/ethernet/aquantia/atlantic/aq_nic.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_nic.c b/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
index b24eaa5283fa..48f35fbf9a70 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
@@ -40,6 +40,10 @@ static unsigned int aq_itr_rx;
 module_param_named(aq_itr_rx, aq_itr_rx, uint, 0644);
 MODULE_PARM_DESC(aq_itr_rx, "RX interrupt throttle rate");
 
+static unsigned int rxpageorder = AQ_CFG_RX_PAGEORDER;
+module_param_named(rxpageorder, rxpageorder, uint, 0644);
+MODULE_PARM_DESC(rxpageorder, "RX page order");
+
 static void aq_nic_update_ndev_stats(struct aq_nic_s *self);
 
 static void aq_nic_rss_init(struct aq_nic_s *self, unsigned int num_rss_queues)
@@ -106,7 +110,7 @@ void aq_nic_cfg_start(struct aq_nic_s *self)
 	cfg->tx_itr = aq_itr_tx;
 	cfg->rx_itr = aq_itr_rx;
 
-	cfg->rxpageorder = AQ_CFG_RX_PAGEORDER;
+	cfg->rxpageorder = rxpageorder;
 	cfg->is_rss = AQ_CFG_IS_RSS_DEF;
 	cfg->aq_rss.base_cpu_number = AQ_CFG_RSS_BASE_CPU_NUM_DEF;
 	cfg->fc.req = AQ_CFG_FC_MODE;
-- 
2.47.2