I am trying to write some code to schedule a set of real life tasks that are input by the user. These tasks are stored in an SQLite database. And at the moment, the only parameters I am taking into consideration are the,
The project to which a task belongs to --> p
The name of the task itself --> t
And the due date for this task --> d
The project and due date parameters are optional. But assuming that the user will always input at least the task name and due date for every task.. I was wondering if it is possible to schedule the set of tasks using a scheduler like the Completely Fair Scheduler (CFS) for example. I realize that the CFS was written for scheduling tasks with much finer granularity (nanoseconds) than the set of tasks being proposed for this purpose… But I realized that it might be possible and maybe more efficient if I can modify it to work with tasks that are on the same time scale as our perception of time.
A typical entry in the database would be in the format (p, t, d). 'p' is optional. Here are a few examples:
(_, 'Call home', 29/2/2012)
(Work, 'Meet boss', 14/3/2012)
(Work, 'Ask for raise', 18/3/2012)
(_, 'Book tickets', 10/3/2012)
(Work, 'Quit', 14/4/2012)
(Personal, 'Get botox injections', 10/3/2012)
(Personal, 'Get breast implants', 10/10/2012)
(_, 'Dad bday', 7/10/2012)
Here is a situation to consider. I would like to wake up in the morning. Run this "yet to be coded" algorithm on the set of tasks.. like the ones given above.. and I would like to receive a schedule for the rest of day, that maximizes throughput. At a later stage, I would like to pass arguments to this algorithms that would allow me to control the scheduler to return a set of tasks depending on my current situation. Like if I am at work, I want to be able to pass arguments to the algorithm, to ask it to only return tasks that can be completed at work..
I hope I am able to convey the gist of it. I understand that the due date alone is not sufficient to schedule tasks using the CFS for example… but if there are other parameters that I should consider, please do let me know. And any suggestions for the kind of scheduling algorithm to employ would be helpful.
Best Answer
This is something I've long desired as well. But a kernel scheduler only has to decide what task to run right now, not when in the future to run other tasks. So those schedulers may help you with part of the problem, but there is a lot more here than they solve. And they have a key bit of information you aren't keeping; namely if a task is blocked or not. (Actually, the kernel is going to track process states, I'm over simplifying here.) You're going to need to know what a task is blocking on so that the user can tell you if the task is unblocked.
If you want to be able to schedule out your day, you're going to have to include an estimate of the time remaining for a task.
You'll want to tie task dependencies into it as well. And that's not even getting into scheduling things with external events like 'order book' -> 'wait for it to arrive' -> 'read book' prior to ordering the book.
I think you're going to find that the problem gets deep quickly, and that having a well-thought-through and always with you UI is going to be critical.