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Subject: Re: Very slow realtek 8169 ethernet performance, but only one
 interface, on ThinkPad T14.
To:     Heiner Kallweit <hkallweit1@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        netdev@vger.kernel.org
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From:   Qu Wenruo <quwenruo.btrfs@gmx.com>
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Date:   Thu, 5 Nov 2020 18:20:19 +0800
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On 2020/11/5 =E4=B8=8B=E5=8D=885:13, Heiner Kallweit wrote:
> On 05.11.2020 08:42, Qu Wenruo wrote:
>>
>>
>> On 2020/11/5 =E4=B8=8B=E5=8D=883:01, Heiner Kallweit wrote:
>>> On 05.11.2020 03:48, Qu Wenruo wrote:
>>>> Hi,
>>>>
>>>> Not sure if this is a regression or not, but just find out that afte=
r upgrading to v5.9 kernel, one of my ethernet port on my ThinkPad T14 (r=
yzen version) becomes very slow.
>>>>
>>>> Only *2~3* Mbps.
>>>>
>>>> The laptop has two ethernet interfaces, one needs a passive adapter,=
 the other one is a standard RJ45.
>>>>
>>>> The offending one is the one which needs the adapter (eth0).
>>>> While the RJ45 one is completely fine.
>>>>
>>>> 02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111=
/8168/8411 PCI Express Gigabit Ethernet Controller (rev 0e)
>>>> 05:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111=
/8168/8411 PCI Express Gigabit Ethernet Controller (rev 15)
>>>>
>>>> The 02:00.0 one is the affected one.
>>>>
>>>> The related dmesgs are:
>>>> [   38.110293] r8169 0000:02:00.0: can't disable ASPM; OS doesn't ha=
ve ASPM control
>>>> [   38.126069] libphy: r8169: probed
>>>> [   38.126250] r8169 0000:02:00.0 eth0: RTL8168ep/8111ep, 00:2b:67:b=
3:d9:20, XID 502, IRQ 105
>>>> [   38.126252] r8169 0000:02:00.0 eth0: jumbo features [frames: 9194=
 bytes, tx checksumming: ko]
>>>> [   38.126294] r8169 0000:05:00.0: can't disable ASPM; OS doesn't ha=
ve ASPM control
>>>> [   38.126300] r8169 0000:05:00.0: enabling device (0000 -> 0003)
>>>> [   38.139355] libphy: r8169: probed
>>>> [   38.139523] r8169 0000:05:00.0 eth1: RTL8168h/8111h, 00:2b:67:b3:=
d9:1f, XID 541, IRQ 107
>>>> [   38.139525] r8169 0000:05:00.0 eth1: jumbo features [frames: 9194=
 bytes, tx checksumming: ko]
>>>> [   42.120935] Generic FE-GE Realtek PHY r8169-200:00: attached PHY =
driver [Generic FE-GE Realtek PHY] (mii_bus:phy_addr=3Dr8169-200:00, irq=3D=
IGNORE)
>>>> [   42.247646] r8169 0000:02:00.0 eth0: Link is Down
>>>> [   42.280799] Generic FE-GE Realtek PHY r8169-500:00: attached PHY =
driver [Generic FE-GE Realtek PHY] (mii_bus:phy_addr=3Dr8169-500:00, irq=3D=
IGNORE)
>>>> [   42.477616] r8169 0000:05:00.0 eth1: Link is Down
>>>> [   76.479569] r8169 0000:02:00.0 eth0: Link is Up - 1Gbps/Full - fl=
ow control rx/tx
>>>> [   91.271894] r8169 0000:02:00.0 eth0: Link is Down
>>>> [   99.873390] r8169 0000:02:00.0 eth0: Link is Up - 1Gbps/Full - fl=
ow control rx/tx
>>>> [   99.878938] r8169 0000:02:00.0 eth0: Link is Down
>>>> [  102.579290] r8169 0000:02:00.0 eth0: Link is Up - 1Gbps/Full - fl=
ow control rx/tx
>>>> [  185.086002] r8169 0000:02:00.0 eth0: Link is Down
>>>> [  392.884584] r8169 0000:02:00.0 eth0: Link is Up - 1Gbps/Full - fl=
ow control rx/tx
>>>> [  392.891208] r8169 0000:02:00.0 eth0: Link is Down
>>>> [  395.889047] r8169 0000:02:00.0 eth0: Link is Up - 1Gbps/Full - fl=
ow control rx/tx
>>>> [  406.670738] r8169 0000:02:00.0 eth0: Link is Down
>>>>
>>>> Really nothing strange, even it negotiates to 1Gbps.
>>>>
>>>> But during iperf3, it only goes up to miserable 3Mbps.
>>>>
>>>> Is this some known bug or something special related to the passive a=
dapter?
>>>>
>>>> Since the adapter is passive, and hasn't experience anything wrong f=
or a long time, I really doubt that.
>>>>
>>>> Thanks,
>>>> Qu
>>>>
>>>>
>>> Thanks for the report. From which kernel version did you upgrade?
>>
>> Tested back to v5.7, which still shows the miserable performance.
>>
>> So I guess it could be a faulty adapter?
>>
>>> Please test
>>> with the prior kernel version and report behavior (link stability and=
 speed).
>>> Under 5.9, does ethtool -S eth0 report packet errors?
>>>
>> Nope, no tx/rx_errors, no missed/aborted/underrun.
>>
>> Adding that the adapter is completely passive (no chip, just convertin=
g
>> RJ45 pins to the I shaped pins), I'm not sure that the adapter itself
>> can fail.
>>
> Each additional mechanical connection may cause reflections or other si=
gnal
> disturbance. You could try to restrict the speed to 100Mbps via ethtool=
,
> and see what the effective speed is then. 100Mbps uses two wire pairs o=
nly.

OK, you're right, now I can get around 60Mbps.

So definitely something wrong with the adapter.

Will use the RJ45 one and avoid use the ThinkPad proprietary interface.

Thanks,
Qu
>=20
>> THanks,
>> Qu
>>
>=20


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