#283 read as "64 MB of mmap and up to 32 MB of page cache per pool",
and it is — but on a 50 000-track library neither is what the
process's memory is: the RSS of the database mapping is 46 MB whether
the bound is 64 MB or 16 MB, because a mapping costs what the working
set touches. Quartering it and halving the page cache moved no query
either: 1 172 → 1 197 ms for the whole track list, 106 → 124 ms for the
album list, 6 → 8 ms for an FTS search, all inside the run-to-run
spread.
Kept, because a bound that costs nothing measurable is worth having on
a phone: five read connections' worth of mapping is 320 MB of address
space at 64 MB each against 80 MB here, and #52 was a low-memory kill.
Closes#283
yonlu
c9b3048a20