Re: [PATCH] sched: smpnice work around for active_load_balance()

[Peter Williams <pwil3058@bigpond.net.au>]

Peter Williams wrote:
> Siddha, Suresh B wrote:
>> HT/MC imbalance is detected in a normal way.. A lightly loaded group
>> finds an imbalance and tries to pull some load from a busy group (which
>> is inline with normal load balance)... pull fails because the only task
>> on that cpu is busy running and needs to go off the cpu (which is 
>> triggered
>> by active load balance)... Scheduler load balance is generally done by 
>> a pull mechansim and here (HT/MC) it is still a pull 
>> mechanism(triggering a final push only because of the single running 
>> task)
>> If you have any better generic and simple method, please let us know.
> 
> I gave an example in a previous e-mail.  Basically, at the end of 
> scheduler_tick() if rebalance_tick() doesn't move any tasks (it would be 
> foolish to contemplate moving tasks of the queue just after you've moved 
> some there) and the run queue has exactly one running task and it's time 
> for a HT/MC rebalance check on the package that this run queue belongs 
> to then check that package to to see if it meets the rest of criteria 
> for needing to lose some tasks.  If it does look for a package that is a 
> suitable recipient for the moved task and if you find one then mark this 
> run queue as needing active load balancing and arrange for its migration 
> thread to be started.
> 
> Simple, direct and amenable to being only built on architectures that 
> need the functionality.

Are you working on this idea or should I do it?

Peter
-- 
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
  -- Ambrose Bierce