linux-kernel - Re: [RFC] [PATCH net-next v5 3/3] r8169: Implement dynamic ASPM mechanism

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Message-ID: <CAAd53p4OKjX8EAuujasaDRD_V=bO5A=euETR5kJeAGfa-84DcA@mail.gmail.com>
Date:   Fri, 17 Sep 2021 12:19:00 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        nic_swsd <nic_swsd@...ltek.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Anthony Wong <anthony.wong@...onical.com>,
        Linux Netdev List <netdev@...r.kernel.org>,
        Linux PCI <linux-pci@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC] [PATCH net-next v5 3/3] r8169: Implement dynamic ASPM mechanism

On Fri, Sep 17, 2021 at 1:12 AM Bjorn Helgaas <helgaas@...nel.org> wrote:
>
> On Thu, Sep 16, 2021 at 11:44:17PM +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.
>
> Obviously this is a *rate*, not an absolute number.  I think you mean
> something like "10 packets in 1000ms".

Will amend this in next iteration.

>
> > The possible reason for this is
> > likely because the buffer on the chip is too small for its ASPM exit
> > latency.
> >
> > Realtek confirmed that all their PCIe LAN NICs, r8106, r8168 and r8125
> > use dynamic ASPM under Windows. So implement the same mechanism here to
> > resolve the issue.
> >
> > Also introduce a lock to prevent race on accessing config registers.
>
> Can you please include the bugzilla link where you attached lspci
> data?  I think it's this:
>
>   https://bugzilla.kernel.org/show_bug.cgi?id=214307

Yes I forgot to add it. Will include in in next iteration.

Kai-Heng

>
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>