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

Siddha, Suresh B
2006-02-17T02:59:05Z

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..

thanks,
suresh