Pid namespaces approaches testing results

[Pavel Emelianov]

Cedric Le Goater wrote:
>> The flat model has many optimization ways in comparison with the multilevel
>> one. Like we can cache the pid value on structs and some other.
>>
>> Moreover having generic level nesting sounds reasonable. Having single level
>> nesting - too as all the namespace we have are single nested. But having the
>> 4 level nesting sounds strange... Why 4? Why not 5? What if I don't know how
>> many I will need exactly, but do know that it will be definitely more than 1?
>>
>> Moreover - I have shown that we can have 1% or less performance on generic
>> nesting model, why not keep it?
> 
> did you send that patchset ? is it included in the one you sent ?

The patchset I sent earlier changed slightly. The tests were performed
on the version I sent. Right now I'm waiting for your results to make
a final decision whether or not to develop the flat model together with
the hierarchical one.

So what are we going to do? The ways we have:
1. Make two models - hierarchical and flat. Maybe we'll see how to merge
   them later;
2. Optimize the hierarchical model to produce no performance hit on the
   first 2 levels (init and VS). I don't see the way to make this
   gracefully, but I maybe this can be solved ... somehow. Anyway, if
   the latest patches from Suka do not produce any noticeable overhead,
   I am OK to go on with them;
3. Make the CONFIG_MAX_NS_DEPTH model. This is likely to be fast in the
   flat case, but I am in doubt whether Andrew will like it :)

> sorry if i missed something :( 
> 
> C.
> 

Thanks,
Pavel