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Re: LMDB mmap usage

Kristoffer Sjögren wrote:

Thanks Howard. What's the best documentation on mmap you know, aside
from read kernel source code?
Not sure what you're asking. Read the mmap(2) manpage and its related pages. If you're thinking there's something fancy hidden in there for you to take advantage of, I don't think you should be using mmap in the first place. 


On Fri, Feb 5, 2016 at 10:33 PM, Howard Chu <hyc@symas.com> wrote:

Kristoffer Sjögren wrote:


Hi

Our application do lots of caching using vmtouch, up to a point where
there isn't a lot of memory left on the machine. We would like to use
LMDB on the same machine to store around 40GiB data of a few hundred
million entries.

How can we best understand the interaction and behavior of the OS
cache and sharing of memory between processes? Is LMDB doing something
to help the OS?



Nope, LMDB does nothing special with its mmap.

--
   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/





--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/