Extensible scheduler class rejected

Posted Jul 28, 2023 4:20 UTC (Fri) by quotemstr (subscriber, #45331)
In reply to: Extensible scheduler class rejected by mb
Parent article: Extensible scheduler class rejected

Except eBPF can teach the kernel to to use information it couldn't before.

Extensible scheduler class rejected

Posted Jul 28, 2023 6:23 UTC (Fri) by mb (subscriber, #50428) [Link] (1 responses)

No? BPF can do less than a kernel patch. That should be obvious.

Extensible scheduler class rejected

Posted Jul 28, 2023 13:35 UTC (Fri) by Manifault (guest, #155796) [Link]

That's a significant oversimplification. Yes, programming in BPF is more constraining than just doing basic kernel programming. There's a reason for that though -- it's because the BPF schedulers _can't crash_ thanks to the verifier (_and_ they can't hang the kernel because of the watchdog).

Additionally:

1. BPF allows user space to communicate state to the kernel via maps. Look at [0] -- there's even a hybrid scheduler that does load balancing in rust in user space.
2. BPF can do a _lot_ now. You can create rbtrees natively in BPF, for example. See the flat cpu controller scheduler in [1].

[0]: https://lore.kernel.org/all/20230711011412.100319-35-tj@k...
[1]: https://lore.kernel.org/all/20230711011412.100319-27-tj@k...