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From: Heiner Kallweit <>
To: Kai-Heng Feng <>
Cc: nic_swsd <>,
	Bjorn Helgaas <>,
	David Miller <>,
	Jakub Kicinski <>,
	Anthony Wong <>,
	Linux Netdev List <>,
	Linux PCI <>,
	LKML <>,
	Bjorn Helgaas <>
Subject: Re: [RFC] [PATCH net-next v4] [PATCH 2/2] r8169: Implement dynamic ASPM mechanism
Date: Mon, 6 Sep 2021 17:34:40 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 06.09.2021 17:10, Kai-Heng Feng wrote:
> On Sat, Sep 4, 2021 at 4:00 AM Heiner Kallweit <> wrote:
>> On 03.09.2021 17:56, Kai-Heng Feng wrote:
>>> On Tue, Aug 31, 2021 at 2:09 AM Bjorn Helgaas <> wrote:
>>>> On Sat, Aug 28, 2021 at 01:14:52AM +0800, Kai-Heng Feng wrote:
>>>>> r8169 NICs on some platforms have abysmal speed when ASPM is enabled.
>>>>> Same issue can be observed with older vendor drivers.
>>>>> The issue is however solved by the latest vendor driver. There's a new
>>>>> mechanism, which disables r8169's internal ASPM when the NIC traffic has
>>>>> more than 10 packets, and vice versa. The possible reason for this is
>>>>> likely because the buffer on the chip is too small for its ASPM exit
>>>>> latency.
>>>> This sounds like good speculation, but of course, it would be better
>>>> to have the supporting data.
>>>> You say above that this problem affects r8169 on "some platforms."  I
>>>> infer that ASPM works fine on other platforms.  It would be extremely
>>>> interesting to have some data on both classes, e.g., "lspci -vv"
>>>> output for the entire system.
>>> lspci data collected from working and non-working system can be found here:
>>>> If r8169 ASPM works well on some systems, we *should* be able to make
>>>> it work well on *all* systems, because the device can't tell what
>>>> system it's in.  All the device can see are the latencies for entry
>>>> and exit for link states.
>>> That's definitely better if we can make r8169 ASPM work for all platforms.
>>>> IIUC this patch makes the driver wake up every 1000ms.  If the NIC has
>>>> sent or received more than 10 packets in the last 1000ms, it disables
>>>> ASPM; otherwise it enables ASPM.
>>> Yes, that's correct.
>>>> I asked these same questions earlier, but nothing changed, so I won't
>>>> raise them again if you don't think they're pertinent.  Some patch
>>>> splitting comments below.
>>> Sorry about that. The lspci data is attached.
>> Thanks for the additional details. I see that both systems have the L1
>> sub-states active. Do you also face the issue if L1 is enabled but
>> L1.2 and L1.2 are not? Setting the ASPM policy from powersupersave
>> to powersave should be sufficient to disable them.
>> I have a test system Asus PRIME H310I-PLUS, BIOS 2603 10/21/2019 with
>> the same RTL8168h chip version. With L1 active and sub-states inactive
>> everything is fine. With the sub-states activated I get few missed RX
>> errors when running iperf3.
> Once L1.1 and L1.2 are disabled the TX speed can reach 710Mbps and RX
> can reach 941 Mbps. So yes it seems to be the same issue.

I reach 940-950Mbps in both directions, but this seems to be unrelated
to what we discuss here.

> With dynamic ASPM, TX can reach 750 Mbps while ASPM L1.1 and L1.2 are enabled.
>> One difference between your good and bad logs is the following.
>> (My test system shows the same LTR value like your bad system.)
>> Bad:
>>         Capabilities: [170 v1] Latency Tolerance Reporting
>>                 Max snoop latency: 3145728ns
>>                 Max no snoop latency: 3145728ns
>> Good:
>>         Capabilities: [170 v1] Latency Tolerance Reporting
>>                 Max snoop latency: 1048576ns
>>                 Max no snoop latency: 1048576ns
>> I have to admit that I'm not familiar with LTR and don't know whether
>> this difference could contribute to the differing behavior.
> I am also unsure what role LTR plays here, so I tried to change the
> LTR value to 1048576ns and yield the same result, the TX and RX remain
> very slow.
> Kai-Heng

  reply	other threads:[~2021-09-06 16:11 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-27 17:14 [RFC] [PATCH net-next v4 0/2] r8169: Implement dynamic ASPM mechanism for recent 1.0/2.5Gbps Realtek NICs Kai-Heng Feng
2021-08-27 17:14 ` [RFC] [PATCH net-next v4 1/2] PCI/ASPM: Introduce a new helper to report ASPM capability Kai-Heng Feng
2021-08-27 17:14 ` [RFC] [PATCH net-next v4] [PATCH 2/2] r8169: Implement dynamic ASPM mechanism Kai-Heng Feng
2021-08-30 18:09   ` Bjorn Helgaas
2021-09-03 15:56     ` Kai-Heng Feng
2021-09-03 20:00       ` Heiner Kallweit
2021-09-06 15:10         ` Kai-Heng Feng
2021-09-06 15:34           ` Heiner Kallweit [this message]
2021-09-07  4:58             ` Kai-Heng Feng
2021-09-07  6:03   ` Heiner Kallweit
2021-09-15 15:54     ` Kai-Heng Feng

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