Re: [PATCH] Fix smpnice high priority task hopping problem

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

Siddha, Suresh B wrote:
> On Fri, Feb 17, 2006 at 01:51:46PM +1100, Peter Williams wrote:
>
> > Peter Williams wrote:
> >
> > > There's a rational argument (IMHO) that this patch should be applied 
> > > even in the absence of the smpnice patches as it prevents 
> > > active_load_balance() doing unnecessary work.  If this isn't good for 
> > > hypo threading then hypo threading is a special case and needs to handle 
> > > it as such.
> >
> > OK.  The good news is that (my testing shows that) the "sched: fix 
> > smpnice abnormal nice anomalies" fixes the imbalance problem and the 
> > consequent CPU hopping.
>
>
> Thats because find_busiest_group() is no longer showing the imbalance :)
> Anyhow if I get time I will review this patch before I start my vacation.
> Otherwise I assume Nick and Ingo will review this closely..
>
>
> > BUT I still think that this patch (modified if necessary to handle any 
> > HT special cases) should be applied.  On a normal system, it will (as 
> > I've already said) stop active_load_balance() from doing a lot of 
> > unnecessary work INCLUDING holding the run queue locks for TWO run 
> > queues for no good reason.
>
>
> Please see my earlier response to this..

I saw nothing there to convince me that this patch isn't worthwhile. 
Perhaps a better explanation would help me?

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

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