LMDB MAP_LOCK flag on readers to minimize major page faults

Hi

MAP_LOCK flag to mmap() on LMDB readers should populate page cache from the file being mapped and preclude those pages from eviction. I was wondering if that was ever tested, especially with frequent writes to the underlying file. And is there a standard way (a compile option) to include that flag without modifying source code directly? I see quite a few major faults with perf stat, and I am looking if they could be avoided.

I am new to LMDB and I guess this discussion may have taken place before, if you could point me out to the right place..

Thank you.

Vitaly