Kernel BoF at Devconf.in¶

August 9, 2018

I attended Devconf.in last weekend. It was a fun and hectic conference, meeting so many open source friends and having long technical and community discussions. This blog post is mainly about the Kernel BoF hosted by me at the conference.

For those unfamiliar with the term, BoF usually stands for Birds of a Feather session. According to Wikipedia, it is usually an informal session at conferences where attendees with similar interests gather in the same room and discuss a particular topic.

While this is the common idea behind BoF sessions, Kernel BoF at Devconf.in was not a typical BoF session. It was somewhere between lightning talks, a Kernel track, and a BoF session. My assumption was that there would be a diverse set of attendees, mainly categorized in two different sets: kernel newbies and kernel hackers. I wanted the session to be interesting for both sets of attendees.

So, Kernel BoF was a semi-structured session. I asked in the Pune and Bangalore kernel meetup mailing lists about interest in topics and talks for the BoF, and we ended up deciding on a bunch of 30-minute and 15-minute talks. The idea was to have talks covering different areas of the Linux Kernel and then see where the discussion goes.

We had two hours and 15 minutes for the whole session and were able to cover the following topics.

A whirlwind tour of Energy-aware Scheduling by Amit Kucharia¶

We started with a 25-30-minute talk by Amit Kucharia on scheduling, mainly focusing on the EAS project by Linaro. It was quite an interesting overview, covering the history of the scheduler, how the EAS project started, and the current status of the project.

Here are the slides from Amit's talk. Note that they also contain links to articles on the project and the ongoing effort of mainlining a bunch of features.

RISC-V workshop update by Siddhesh Poyarekar¶

As you may know, RISC-V is a free and open ISA based on established RISC principles. There was a RISC-V workshop organized at IIT Madras around mid-July. Based on Atish Patra's talk at the RISC-V workshop, Siddhesh Poyarekar gave an update on the kernel status for the same.

RISC-V support was added in kernel 4.15, and you can find the introductory LWN article here. Atish's talk from the RISC-V workshop can be found here. Do check it out as it contains a lot of information about future plans. If you are looking for a way to start contributing to the Linux Kernel, this can be something interesting. There is an IRC channel and mailing list too.

In the Kernel BoF, this was a 10-15 minute session, mainly talking about the above-mentioned things. There is also a Shakti Processor project started at IIT Madras, aimed at developing a complete reference SoC for each family variant of processors based on the RISC-V ISA from UC Berkeley.

Latest development in Audio subsystem by Vinod Koul¶

This was a 30-minute session intended to cover a bunch of things related to the sound subsystem in the kernel. I was surprised that Vinod Koul was able to cover so many topics like the audio stack, different topologies, Sound Open Firmware, ALSA, and more. Slides from the session can be found here.

VLA usage removal effort by Allen Pais¶

Allen Pais talked about Variable Length Array removals in the Linux Kernel, how it started by Kees Cook, and how we ended up deciding on MAX. Allen's slides can be found here. They also contain links to a bunch of interesting LWN articles, including my favourite: "The joy of max()". This was a 10-15-minute session.

I got feedback from kernel newbies that this was the most interesting session, mainly because it did not require much kernel knowledge and was touching areas of the C language.

Reduce KVM guest memory footprint by Pankaj Gupta¶

I was glad that we had 10-15 minutes to talk about this topic as well. Pankaj mainly talked about the goal behind reducing KVM guest memory footprint, steps to achieve it, and the fake DAX flushing interface. Slides from the talk can be found here, and you can also check out the RFC version of the patches for fake DAX flushing interface submitted by Pankaj in LKML.

I enjoyed hosting this and discussing a bunch of topics with fellow kernel hackers, while also understanding the questions from kernel newbies. I think we should do more semi-structured sessions like this at conferences.

P.S. I maintain a repository named Kernel Bridge with a bunch of TODOs from different Linux Kernel projects and subsystems. I do not keep track of who is working on what, but I usually get a lot of emails from people who are interested in contributing to the Linux Kernel, so having a single link helps.

If you are a kernel developer and you have a task list for the subsystem or project you are working on, feel free to send a PR or email me and I will add it there.

Trivia¶

We had to climb eight floors to attend the BoF, and all speakers had to sit on the floor because by the time we reached the room, it was full. I created Twitter moments of Kernel BoF here.