[v3] __pool_alloc rework

[Paolo Carlini]

Carlo Wood wrote:

>I mean that in the view of my specific problem (thus, not the performance
>problem you talk about) the only thing that matters are multi-threaded
>applications.  We should only talk about and consider the MT case.
>
I see.
Before any other technical discussion, why don't you give mt_alloc a try?
You can find the last version both in mainline and 3_4-branch, just pass
--enable-libstdcxx-allocator=mt at build time. If I understand well your
problems there are good chances that it can do better than pool_alloc.

Paolo.