Messages in this thread | | | Date | Mon, 27 Jan 2014 13:52:31 +0100 | From | Luca Abeni <> | Subject | Re: [PATCH] sched/deadline: Add sched_dl documentation |
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On 01/27/2014 01:40 PM, Henrik Austad wrote: [...] >>> Current runtime: time spent running _this_ period? or is _remaining_ >>> runtime this period? I get the feeling it's the latter. >>> >>> So, roughly, it is the ration >>> >>> remaining_runtime / relative_time_to_deadline >>> >>> which needs to be greater than the assigned CPU bandwidth, and if so, the >>> budget should be replensihed? >>> >>> Shouldn't there be something about not refilling the budget before a new >>> period has started? >> Uh... Maybe the description above can be improved :) >> Do you think that using "remaining runtime" instead of "current runtime" >> would help? If yes, I'll make this change. > > Yes, in my vocabularly, "remaining" != "current" :), so changing to > 'remaining runtime' would be nice. Ok; I'll make this change.
>> Also, I see that some of your questions are answered by some items below... > > Yes, but I left the comments to indicate that the order was a bit > confusing. > >> Do you think that changing the order of the items in the presentation would >> improve the readability? If you suggest a better ordering, I'll try to >> rewrite the algorithm's description according to it. > > Could be, at least the ratio-caclulation was a bit confusing until I'd read > the entire section. > > My preferred order (I've just cut'n'pased from the original email here) > > + - The state of the task is described by a "scheduling deadline", and > + a "current runtime". These two parameters are initially set to 0; BTW, maybe some of the confusion can be avoided by explaining what the "remaining runtime" is here... Something like: - The state of the task is described by a "scheduling deadline", and a "current runtime" (representing the amount of execution time that the task can use before the scheduling deadline). These two parameters are initially set to 0;
Can something like this help? If yes, I'll update the document.
[...] > + - When a SCHED_DEADLINE task wakes up (becomes ready for execution), > + the scheduler checks if > + > + current runtime runtime > + ---------------------------------- > ---------------- > + scheduling deadline - current time period > + > + then, if the scheduling deadline is smaller than the current time, or > + this condition is verified, the scheduling deadline and the > + current budget are re-initialised as > + > + scheduling deadline = current time + deadline > + current runtime = runtime > + > + otherwise, the scheduling deadline and the current runtime are > + left unchanged; > + > > Emphasis on -my- preferred order. :) Ok; let's see what other people think, and then we decide the items' order.
> Either way, I'm quite happy with this documentation-update, this is just > nitpick :) Ok, good.
Thanks, Luca
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