[PATCH 03/10] Add external interface changes: new lock types for pthread_mutex_t

[Andi Kleen]

> If the former are part of the standard ABI, these need to be
> future-proof. 

Enabling/disabling is part of the ABI and is very future-proof.

Internal algorithm tunables are not part of the ABI, as I see it.
They are not future-proof.

If there was ever an ABI for those it would likely consist of making
old obsolete ones noops as Carlos proposed. But I don't think it makes
sense to really support programs doing that, it's mostly an test interface
for people trying out their applications.


> Thus, if we assume that we won't change the ABI, what can we accomplish
> right now?  For example, is there a way to have a conservative HLE
> adaptation mechanism that is very unlikely to cause significant
> slow-downs when enabled by default?  Then we could exploit the new
> hardware almost transparently.

Yes I think so, but it needs more testing with a large body of
applications.  And to do the testing we need the tunables.

-Andi