minutes: IO Visor TSC/Dev Meeting

Brenden Blanco

Hi All,

Thank you for joining the call today. Here are my notes from the discussion.


=== Discussion ===
* Plan to tag release to coincide with kernel 5.0

* Speaking this weekend at SCaLE in Los Angeles

* LLVM work
* compile once - run anywhere WIP
* support for static variables

* Global data support work in kernel continues
* Ability to lock maps as read-only
* bugfixes after merge window

* Some thoughts on future work of BPF
* especially with introduction of BTF
* overall needs concerted effort to improve debuggability
* BTF for programs itself with source/type/layout information
* structures for maps and global data
* suggest to always require type information
(already turned on by default in bcc and supported by llvm)
* Some extra hoops to jump through for driver embedded BPF
* to be enabled with a sysctl
* kernel support is ready
* some long tail of support - e.g. systemd has raw assembly BPF
* kconfig option - eventual deprecation
* if kernel is default strict, llvm should automatically emit BTF as well
* memcg accounting patch status?
* Daniel - still being worked on
* proposal to enable the same accounting for verifier memory
* helps to enable verifier multithreading

* question regarding global data atomicity
* Daniel - requires read once / write once instructions to work properly
* some todo work on documentation, interpreter + jit implementations
* depends on architecture (machine word size guarantees only)

* which llvm release supports BTF
* landed in December - will be in 8.0, better in 9.0
* working on tutorial for xdp at netdev
* https://www.netdevconf.org/0x13/session.html?tutorial-XDP-hands-on
* soliciting feedback
* https://github.com/xdp-project/xdp-tutorial/

* request to devote some time in the next meeting to iron out some XDP issues
* please send an agend in reply to the reminder email before next call
* prepare discussion over email in between time

=== Attendees ===
Alexei Starovoitov
Marco Leogrande
Mauricio Vasquez
Paul Chaignon
Brenden Blanco
Jiong Wang
Yonghong Song
Daniel Borkmann
Jesper Brouer
Quentin Monnet
Dan Siemon
Jakub Kicinski

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