Re: High priority tasks break SMP balancer?

[Ingo Molnar]

* Micah Dowty <micah@xxxxxxxxxx> wrote:

> > I am a bit at a loss as to how this could relate to the patch. This 
> > looks like a load balance logic issue that causes the load 
> > calculation to go wrong?
> 
> My best guess is that this has something to do with the timing with 
> which we sample the CPU's instantaneous load when calculating the load 
> averages.. but I still understand only the basics of the scheduler and 
> SMP balancer. All I really know for sure at this point regarding your 
> patch is that git-bisect found it for me.

hm, your code uses timeouts for this, right? The CPU load average that 
is used for SMP load balancing is sampled from the scheduler tick - and 
has been sampled from the scheduler tick for eons. v2.6.23 defaulted to 
a different method but v2.6.24 samples it from the tick again. So my 
guess is, your testcode behave similarly on 2.6.22 too, correct?

	Ingo
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