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authorCorinna Vinschen <vinschen@redhat.com>2019-11-19 10:09:39 +0100
committerDavid S. Miller <davem@davemloft.net>2019-11-19 16:41:11 -0800
commita0783cd0c810504427777e8aae20d5f4f8b652a0 (patch)
tree523987f32fb716e6b48c807ffe28766395183d54 /drivers/net/ethernet/realtek
parentc9d55b62c90028fec0fc3a7eb01d03f8c241d27f (diff)
downloadlinux-a0783cd0c810504427777e8aae20d5f4f8b652a0.tar.gz
r8169: disable TSO on a single version of RTL8168c to fix performance
During performance testing, I found that one of my r8169 NICs suffered
a major performance loss, a 8168c model.

Running netperf's TCP_STREAM test didn't return the expected
throughput of > 900 Mb/s, but rather only about 22 Mb/s.  Strange
enough, running the TCP_MAERTS and UDP_STREAM tests all returned with
throughput > 900 Mb/s, as did TCP_STREAM with the other r8169 NICs I can
test (either one of 8169s, 8168e, 8168f).

Bisecting turned up commit 93681cd7d94f83903cb3f0f95433d10c28a7e9a5,
"r8169: enable HW csum and TSO" as the culprit.

I added my 8168c version, RTL_GIGA_MAC_VER_22, to the code
special-casing the 8168evl as per the patch below.  This fixed the
performance problem for me.

Fixes: 93681cd7d94f ("r8169: enable HW csum and TSO")
Signed-off-by: Corinna Vinschen <vinschen@redhat.com>
Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/realtek')
-rw-r--r--drivers/net/ethernet/realtek/r8169_main.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index c4e961ea44d5..c33c438850cc 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -7179,8 +7179,11 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 		dev->gso_max_segs = RTL_GSO_MAX_SEGS_V1;
 	}
 
-	/* RTL8168e-vl has a HW issue with TSO */
-	if (tp->mac_version == RTL_GIGA_MAC_VER_34) {
+	/* RTL8168e-vl and one RTL8168c variant are known to have a
+	 * HW issue with TSO.
+	 */
+	if (tp->mac_version == RTL_GIGA_MAC_VER_34 ||
+	    tp->mac_version == RTL_GIGA_MAC_VER_22) {
 		dev->vlan_features &= ~(NETIF_F_ALL_TSO | NETIF_F_SG);
 		dev->hw_features &= ~(NETIF_F_ALL_TSO | NETIF_F_SG);
 		dev->features &= ~(NETIF_F_ALL_TSO | NETIF_F_SG);