netdev - Re: [PATCH v10 00/20] dlb: introduce DLB device driver

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Message-ID: <CAPcyv4gCMjoDCc2azLEc8QC5mVhdKeLibic9gj4Lm=Xwpft9ZA@mail.gmail.com>
Date:   Thu, 11 Mar 2021 23:18:24 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Mike Ximing Chen <mike.ximing.chen@...el.com>,
        Netdev <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Subject: Re: [PATCH v10 00/20] dlb: introduce DLB device driver

On Wed, Mar 10, 2021 at 1:02 AM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Wed, Feb 10, 2021 at 11:54:03AM -0600, Mike Ximing Chen wrote:
> > Intel DLB is an accelerator for the event-driven programming model of
> > DPDK's Event Device Library[2]. The library is used in packet processing
> > pipelines that arrange for multi-core scalability, dynamic load-balancing,
> > and variety of packet distribution and synchronization schemes
>
> The more that I look at this driver, the more I think this is a "run
> around" the networking stack.  Why are you all adding kernel code to
> support DPDK which is an out-of-kernel networking stack?  We can't
> support that at all.
>
> Why not just use the normal networking functionality instead of this
> custom char-device-node-monstrosity?

Hey Greg,

I've come to find out that this driver does not bypass kernel
networking, and the kernel functionality I thought it bypassed, IPC /
Scheduling, is not even in the picture in the non-accelerated case. So
given you and I are both confused by this submission that tells me
that the problem space needs to be clarified and assumptions need to
be enumerated.

> What is missing from todays kernel networking code that requires this
> run-around?

Yes, first and foremost Mike, what are the kernel infrastructure gaps
and pain points that led up to this proposal?