Re: [PATCH v7 0/7] Introduce ZONE_CMA

[Michal Hocko]

Hi,
I didn't get to read though patches yet but the cover letter didn't
really help me to understand the basic concepts to have a good starting
point before diving into implementation details. It contains a lot of
history remarks which is not bad but IMHO too excessive here. I would
appreciate the following information (some of that is already provided
in the cover but could benefit from some rewording/text reorganization).

- what is ZONE_CMA and how it is configured (from admin POV)
- how does ZONE_CMA compare to other zones
- who is allowed to allocate from this zone and what are the
  guarantees/requirements for successful allocation
- how does the zone compare to a preallocate allocation pool
- how is ZONE_CMA balanced/reclaimed due to internal memory pressure
  (from CMA users)
- is this zone reclaimable for the global memory reclaim
- why this was/is controversial
-- 
Michal Hocko
SUSE Labs