https://bugs.openldap.org/show_bug.cgi?id=9475
--- Comment #1 from Howard Chu <[email protected]> --- (In reply to leslie from comment #0) > In some case (such as cloud computing platforms), the reading speed of large > files is very fast while the small files is very slow, and we have enough > memory, so we hope to prefetch the entire LMDB file into the memory during > MMAP through the MAP_POPULATE flag . According to our test, this is faster > than using readahead flag. Here are some test data: > > # mmap with no readahead > read one sample: 0.2s > total time: 4800s > > > # mmap with readahead > read one sample: 0.0001s~0.03s > total time: 95.86s > > # mmap with MAP_POPULATE > db init: 20s > read one sample: 0.0001s > total time: 78s Have you tested the performance by simply dd'ing the entire file into memory before running your test? `dd if=data.mdb of=/dev/null` would be sufficient to preload the data into memory. -- You are receiving this mail because: You are on the CC list for the issue.
