On Sat, Jan 15, 2022 at 04:29:24PM +0800, Huichun Feng wrote: > Hi Roman and the list, Hello Huichun! > > I have a naive question regarding BPF hook for sched. > > Given that BPF can also be attached to tracepoint, why do we add a BPF prog > type specific to sched? Tracing programs can have return values as well, see kretprobes. > > The reason I can come up with is that sched BPF can have retval to drive the > scheduling decision in static branch, whereas tracepoint is not able to do this. > Is it mainly because of this or anything else? Well, you are right that right now there is no strict necessity to introduce a new prog type (aside from static branch mechanism you mentioned), however I believe it's useful in a long run. Sched programs might be able to use a different set of helpers, maybe there will be some additional restrictions, etc. It's an RFC version of the patchset and any ideas, suggestions and critic are highly welcome! Thanks!
