This fixes two simple but significant typos in the HPA:
- The conf string parsing accidentally set a min value of PAGE for
hpa_sec_batch_fill_extra; i.e. allocating 4096 extra pages every time we
attempted to allocate a single page. This puts us over the SEC flush limit,
so we then immediately flush all but one of them (probably triggering
purging).
- The HPA was using the default PAI batch alloc implementation, which meant it
did not actually get any locking advantages.
This snuck by because I did all the performance testing without using the PAI
interface or config settings. When I cleaned it up and put everything behind
nice interfaces, I only did correctness checks, and didn't try any performance
ones.