https://bugs.openldap.org/show_bug.cgi?id=9475
Issue ID: 9475
Summary: Add support for MAP_POPULATE
Product: LMDB
Version: unspecified
Hardware: All
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: ---
Component: liblmdb
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
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
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