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From: "Rafał Miłecki" <zajec5@gmail.com>
To: Network Development <netdev@vger.kernel.org>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	nic_swsd@realtek.com
Subject: r8169: Ethernet speed regressions with RTL8168gu in ThinkPad E480
Date: Mon, 30 May 2022 16:10:09 +0200	[thread overview]
Message-ID: <5a04080f-a2eb-6597-091e-6b31c4df1661@gmail.com> (raw)

I've ThinkPad E480 with i3-8130U CPU and 10ec:8168 detected as:
[    8.458515] r8169 0000:03:00.0 eth0: RTL8168gu/8111gu, 8c:16:45:5d:f2:c2, XID 509, IRQ 136
[    8.458521] r8169 0000:03:00.0 eth0: jumbo features [frames: 9194 bytes, tx checksumming: ko]
[   12.272352] Generic FE-GE Realtek PHY r8169-0-300:00: attached PHY driver (mii_bus:phy_addr=r8169-0-300:00, irq=MAC)

It's connected to WAN port of BCM4708 based home router running OpenWrt
with kernel 5.4.113. I run "iperf -s" on this E480 for network testing.

***************

After upgrading kernel from 4.12 to 5.18 I noticed Ethernet speed
regression. I bisected it down to two commits:


commit 6b839b6cf9eada30b086effb51e5d6076bafc761
Author: Heiner Kallweit <hkallweit1@gmail.com>
Date:   Thu Oct 18 19:56:01 2018 +0200

     r8169: fix NAPI handling under high load

(introduced in 4.19 and dropped speed by 20 Mb/s = 5%)


commit 288ac524cf70a8e7ed851a61ed2a9744039dae8d
Author: Heiner Kallweit <hkallweit1@gmail.com>
Date:   Sat Mar 30 17:13:24 2019 +0100

     r8169: disable default rx interrupt coalescing on RTL8168

(introduced in 5.1 and dropped speed by 60 Mb/s = 15%)

***************

Is that possible to fix / rework r8169 to provide original higher
Ethernet speed out of the box?

Honestly I'd expect this i3-8130U to handle 1 Gb/s traffic or more and
my guess is that the real bottleneck is my home router here (slow
BCM4708 SoC CPU). Still it seems like r8169 can be a bottleneck on top
of bottleneck.

***************

v5.18
334 Mbits/sec

v5.10
336 Mbits/sec

v5.1 + git revert 288ac524cf70a8e7ed851a61ed2a9744039dae8d
397 Mbits/sec (back to medium speed)

v5.1
335 Mbits/sec (-60 Mb/s)

v5.0
395 Mbits/sec

***************

v4.19 + git revert 6b839b6cf9eada30b086effb51e5d6076bafc761
414 Mbits/sec (back to high speed)

v4.19
395 Mbits/sec (-20 Mb/s)

v4.18
415 Mbits/sec

v4.12
415 Mbits/sec

             reply	other threads:[~2022-05-30 15:13 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-30 14:10 Rafał Miłecki [this message]
2022-05-30 19:21 ` r8169: Ethernet speed regressions with RTL8168gu in ThinkPad E480 Heiner Kallweit

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