RE: [RFC PATCH v12 01/17] dlb: add skeleton for DLB driver

-----Original Message-----
From: Andrew Lunn <andrew@lunn.ch>
Sent: Thursday, December 23, 2021 5:23 AM
To: Chen, Mike Ximing <redacted>
Cc: linux-kernel@vger.kernel.org; arnd@arndb.de; gregkh@linuxfoundation.org; Williams, Dan J
[off-list ref]; pierre-louis.bossart@linux.intel.com; netdev@vger.kernel.org;
davem@davemloft.net; kuba@kernel.org
Subject: Re: [RFC PATCH v12 01/17] dlb: add skeleton for DLB driver

On Thu, Dec 23, 2021 at 05:15:34AM +0000, Chen, Mike Ximing wrote:

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-----Original Message-----
From: Andrew Lunn <andrew@lunn.ch>
Sent: Wednesday, December 22, 2021 4:27 PM
To: Chen, Mike Ximing <redacted>
Cc: linux-kernel@vger.kernel.org; arnd@arndb.de;
gregkh@linuxfoundation.org; Williams, Dan J
[off-list ref]; pierre-louis.bossart@linux.intel.com;
netdev@vger.kernel.org; davem@davemloft.net; kuba@kernel.org
Subject: Re: [RFC PATCH v12 01/17] dlb: add skeleton for DLB driver

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pointing to skbufs? How are the lifetimes of skbufs managed? How
do you get skbufs out of the NIC? Are you using XDP?

This is not a network accelerator in the sense that it does not
have direct access to the network sockets/ports. We do not use XDP.

So not using XDP is a problem. I looked at previous versions of this
patch, and it is all DPDK. But DPDK is not in mainline, XDP is. In order for this to be merged into

mainline you need a mainline user of it.

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Maybe you should abandon mainline, and just get this driver merged into the DPDK fork of Linux?

Hi Andrew,

I am not sure why not using XDP is a problem. As mentioned earlier,
the DLB driver is not a part of network stack.

DPDK is one of applications that can make a good use of DLB, but is
not the only one. We have applications that access DLB directly via
the kernel driver API without using DPDK.

Cool. Please can you point at a repo for the code? As i said, we just need a userspace user, which gives us
a good idea how the hardware is supposed to be used, how the kAPI is to be used, and act as a good test
case for when kernel modifications are made. But it needs to be pure mainline.

There have been a few good discussion on LWN about accelerators recently. Worth reading.

We don't have a public repo for dlb yet, but you can download the dlb 
software package at https://www.intel.com/content/www/us/en/download/686372/intel-dynamic-load-balancer.html.
It includes dlb kernel driver and sample user applications (for both
DPDK and non-DPDK users).

I will check out the discussion on LWN.
Thanks for the suggestion.

Mike