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Re: "threads" directive OpenLDAP 2.0.* & 2.1.*

--On Monday, November 07, 2005 9:26 AM -0500 Robert Petkus <rpetkus@bnl.gov> wrote:

Quanah Gibson-Mount wrote:

low. The default in OpenLDAP 2.2 and 2.3 is 16, I don't recall offhand the default in 2.1. I generally don't advise going above 16 threads, and recent testing in the Symas benchmarking labs seems to indicate that a lower setting is actually better, as it reduces contention in the backend database.

Really?  I've found that the default of 16 threads is inadequate in a
large environment -- at least when using a ldap proxy in front, the load
is inversely proportional.  Are the benchmarking results public?

As with anything, it entirely depends on your specific configuration. What I was looking at in this benchmark is an OpenLDAP server doing only one thing -- Having a bdb database that returns data, no proxying involved.

The results from the same database/server at the following thread levels were:

8 threads (20 querying clients): 8,726 reads/second
12 threads (20 querying clients): 6,583 reads/second
20 theads (20 querying clients): 5,904 reads/second

Results from oprofile indicated that with both 12 and 20 threads, the majority of time was spent in BDB database locks. With 8 threads, the highest percentage time was spent in the slapd libraries.


Quanah Gibson-Mount
Product Engineer
Symas Corporation
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