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

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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                                   [email protected]

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