Use SingleStreamRegion and NoSyncRegion in MLMG solve

[AlexanderSinn]

Summary

Additional background

Checklist

The proposed changes:

• fix a bug or incorrect behavior in AMReX
• add new capabilities to AMReX
• changes answers in the test suite to more than roundoff level
• are likely to significantly affect the results of downstream AMReX users
• include documentation in the code and/or rst files, if appropriate

[WeiqunZhang]

Maybe we should make this a runtime option. For example, maybe we can add a member function MLMG::setNoGpuSync to control whether we want to avoid gpu sync if possible (and use single stream for safety).

[AlexanderSinn]

hmm NoSyncRegion is a bit difficult to use with a runtime parameter

[marchdf]

@AlexanderSinn thanks for pushing this through! So do you have a call somewhere where you do: setNoGpuSync(true)? In your code? Can you point me to that?

[WeiqunZhang]

Amr-wind does not build MLMG directly. But, there is a function in amr-wind that gives you a reference to an mlmg object. You can call it at any time before solve.