From a0783cd0c810504427777e8aae20d5f4f8b652a0 Mon Sep 17 00:00:00 2001 From: Corinna Vinschen Date: Tue, 19 Nov 2019 10:09:39 +0100 Subject: 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 Reviewed-by: Heiner Kallweit Signed-off-by: David S. Miller --- drivers/net/ethernet/realtek/r8169_main.c | 7 +++++-- 1 file 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); -- cgit