Messages in this thread | | | Date | Mon, 3 Sep 2007 22:04:05 +0200 | From | Ingo Molnar <> | Subject | Re: [ANNOUNCE/RFC] Really Simple Really Fair Scheduler |
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* Roman Zippel <zippel@linux-m68k.org> wrote:
> Hi, > > On Mon, 3 Sep 2007, Ingo Molnar wrote: > > > My next question then is about this code of yours in the wakeup path: > > > > +static void > > +enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) > > +{ > > + kclock_t min_time; > > + > > + verify_queue(cfs_rq, cfs_rq->curr != se, se); > > + min_time = get_time_avg(cfs_rq) - se->req_weight_inv; > > + if ((kclock_t)(se->time_norm - min_time) < 0) > > + se->time_norm = min_time; > > > > why do you only use the "min_time" if the pre-sleep time_norm is smaller > > than the min_time? Here 'min_time' is close to the current average. > > It's a variation of the sleeper bonus. [...]
hm, where are its effects described in your explanation? Seems like a key item.
> [...] Let's assume two running tasks which have been running for 95ms > and 105ms and a time slice of 10ms, the average is thus 100ms. If the > new task has been sleeping for a while it starts at 90ms, if the task > had been running lately it doesn't get this bonus again.
what happens if there are lots of such tasks? What limits the total bonus?
> > Shouldnt here the woken up task be set to the average time, like i > > did it in the crude prototype: > > > > + se->exec_runtime = avg_exec_runtime(cfs_rq); > > That would be equivalent to simply clearing wait_runtime in CFS.
so my prototype patch is not an exact map of the nice-0 special-case of your code? Would this be the correct thing then perhaps:
+ se->exec_runtime = + max(avg_exec_runtime(cfs_rq), se->exec_runtime);
Or if not, could you suggest a code-line at that place? Thanks,
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