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Re: MDB, read/write mmap
Howard Chu wrote:
> It seems to me this can only be a viable mode of operation if you're always
> going to run asynch and don't care much about transaction durability or DB
> recoverability. Running in this mode offers absolutely zero crash resistance;
> the entire DB will almost always be irreparably damaged after a system crash.
> Would you run like that, if it offered you the potential of maybe 10x faster
> write performance?ï (It could be useful for slapadd -q, certainly.)
OK, 10x speedup was far too optimistic. Quickly cobbling the changes together,
it looks more like about a 70% speedup.
slapadd -q with 5 million entries took 24m16s as originally reported at
LDAPCon last year.
With current mdb.master it takes 22m24s:
With the writable mmap and no msyncs it took 13m17s.
This code is currently available on the map2 branch of my git repo on
ada.openldap.org. I'll clean it up a bit further then push it to mdb.master
after some more testing.
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/