Hi, I have gotten clearer idea of fairness between processes. Thanks for your explanation with enough patience. :-) 2011/9/20 Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx>: > Hi ..... > > I am reaching my virtual limit here, so beg me pardon :) > > On Mon, Sep 19, 2011 at 23:26, Parmenides >> Hmm..., does that mean timeslice weighting introduce unfainess? If we >> think fairness relies on each task not fetching more timeslice than >> other tasks, the eaiest way to achieve fairness is to give every task >> the same timeslice. > > At the extreme theoritical side, yes, ....but again that is if all are > CPU bound.... the complication comes since in reality most processes > are mixture of CPU and I/O bound...or sometimes I/O bound only. > >> Can I understand like this: each task advance its progress tinier than >> traditional timeslice, which makes C has more chances to be selected >> to preempt A or B owing to its higher priority? Higer priority makes >> C's virtual time smaller than A and B. >> > > in non preemptive kernel i.e cooperative scheduling, your above > suggested idea is the right way to achieve fairness in such situation. > However, since user space (and now kernel space too) implements > preemptive, adjusting time slice is not really necessary to make C > kicks back into run queue. > > What the scheduler needs perhaps at this point is good priority > recalculation is C could run ASAP. If not, even though C is in run > queue, it still can beat the other processes in the competition of CPU > time. > > > -- > regards, > > Mulyadi Santosa > Freelance Linux trainer and consultant > > blog: the-hydra.blogspot.com > training: mulyaditraining.blogspot.com > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
