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