Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS]

Ingo Molnar
2007-04-15T15:39:58Z

* Willy Tarreau <w@1wt.eu> wrote:

> Ingo could have publicly spoken with them about his ideas of killing
> the O(1) scheduler and replacing it with an rbtree-based one, [...]

yes, that's precisely what i did, via a patchset :)

[ I can even tell you when it all started: i was thinking about Mike's
throttling patches while watching Manchester United beat the crap out
of AS Roma (7 to 1 end result), Thuesday evening. I started coding it
Wednesday morning and sent the patch Friday evening. I very much
believe in low-latency when it comes to development too ;) ]

(if this had been done via a comittee then today we'd probably still be
trying to find a suitable timeslot for the initial conference call where
we'd discuss the election of a chair who would be tasked with writing up
an initial document of feature requests, on which we'd take a vote,
possibly this year already, because the matter is really urgent you know
;-)

> [...] and using part of Bill's work to speed up development.

ok, let me make this absolutely clear: i didnt use any bit of plugsched
- in fact the most difficult bits of the modularization was for areas of
sched.c that plugsched never even touched AFAIK. (the load-balancer for
example.)

Plugsched simply does something else: i modularized scheduling policies
in essence that have to cooperate with each other, while plugsched
modularized complete schedulers which are compile-time or boot-time
selected, with no runtime cooperation between them. (one has to be
selected at a time)

(and i have no trouble at all with crediting Will's work either: a few
years ago i used Will's PID rework concepts for an NPTL related speedup
and Will is very much credited for it in today's kernel/pid.c and he
continued to contribute to it later on.)

(the tree walking bits of sched_fair.c were in fact derived from
kernel/hrtimer.c, the rbtree code written by Thomas and me :-)

Ingo