Re: [PATCH 1/5] cpuset memory spread basic implementation

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxx> wrote:

> > We normally run with different policies, in the same box, on different 
> > cpusets at the same time.  But this might be because some cpusets 
> > -need- the memory spreading, and the others that don't are left to the 
> > default policy.
> 
> so in practice, the memory spreading is in fact a global setting, used 
> by all cpusets that matter? That seems to support Andrew's observation 
> that our assumptions / defaults are bad, pretty much independently of 
> the workload.

in other words: the spreading out likely _hurts_ performance in the 
typical case (which prefers node-locality), but when you are using 
multiple cpusets you want to opt for fairness between projects, over 
opportunistic optimizations such as node-local allocations. I.e. the 
spreading out, as it is used today, is rather a global fairness setting 
for the kernel, and not really a workload-specific access-pattern thing.  
Right?

	Ingo
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