pluggable schedulers vs. tunable schedulers

Posted Sep 12, 2009 9:00 UTC (Sat) by mingo (guest, #31122)
In reply to: pluggable schedulers vs. tunable schedulers by trasz
Parent article: BFS vs. mainline scheduler benchmarks and measurements

Let me repeat - in Solaris, schedulers are the parts of code that calculate priorities. They don't do other things - specifically, they don't switch threads. You don't have to schedule them in any way - just switch threads conforming to the priorities calculated by the schedulers.

That's not pluggable schedulers. It's one scheduler with some flexibility in calculating priorities. The mainline Linux scheduler has something like that too btw: we have 'scheduling classes' attached to each process. See include/linux/sched.h::struct sched_class.

And if you don't like this approach, you could still do what FreeBSD has been doing for several years now - implement schedulers changeable at compile time.

It's not about me 'liking' anything. My point is that i've yet to see a workable model for pluggable schedulers. (I doubt that one can exist - but i have an open mind about it and i'm willing to be surprised.)

Compile-time is not a real pluggable scheduler concept: which would be multiple schedulers acting _at once_. See the example i cited: that you can set Firefox to BFS one and Thunderbird to CFS.

Compile-time (plus boot time) schedulers is what the PlugSched patches did for years.