Re: fairsched + O(1) process scheduler

[Antonio Vargas]

On Tue, Apr 08, 2003 at 02:56:34PM -0400, Hubertus Franke wrote:
> 
> Antonio, while you are coding here is some additional input.

Great!
 
> By intoducing the user based pending queue and leaking
> the tasks back into the runqueue based on the per user ticks, you
> are changing semantics slightly.
> 
> If the task is reinserted back into the runqueue oit should be 
> reinserted into the expired queue iff and only no
> expired/active queue switch has happened. 
> Otherwise it should be reinserted into the active list.

This sounds right :)
 
> This will becoe important when we later distinguish between
> users that have limited share and those that have unlimited.

Yes, we should push the "p->user->uid == 0" test into the
send_task_to_user() function then... and later on implement
a "p->user->unlimited_cpu_share == 1" test.
 
> Can be implemented by keeping a per runqueue array switch count
> and store it with the pending task. On reinsertion, if 
> the task has the same as the current it goes to the expired.
> If its older than the current, then the task missed the array switch
> and it should go into the active queue.
> 
> Also, I don't follow necessarily your reason to put an INTERACTIVE
> task back on the active queue immediately, rather than going first
> through the pending queue again.
> 
> This way, a high priority job with even a small sleep_avg already being 
> declared INTERACTIVE, will continue to suck up cycles beyond its
> user's limits. This can be as long as 8 secs currently.

Perhaps I'm not declaring this in any explicit way, but I feel
that this type of control should only be applied to cpu hogs.

> Instead, things to consider is to feed these as well through the 
> pending queue and distinguish in the pending queue ?
> More thoughts required here... I let you know when any of them is
> successful at my end.

I'm somewhat deadlocked right now, so I'll have to wait until I have
some think up some way to make it work as intended.
 
Greets, Antonio