slapd-mdb network performance

["Jancewicz, Russell" <russell.jancewicz@uconn.edu>]

Hello,

I am experiencing a bit of an issue with mdb network traffic. 
When I request large queries (entire subtrees) from remote hosts my searches take hundreds of times longer to complete than they do if I search on the local machine (in all expect for one case).

I have attempted to tune the kernel network settings, adjusted tx buffer sizes all to no avail. 

Just before turning to this list i gave one last shot in the dark attempt running my query using the rootDN. This produced the expected results.

When queried with a typical account DN my system was transmitting around 2.0Mbps to the remote client. 
When queried with the rootDN my system was transmitting around 100Mbps to the client.

The system has an olcLimits rule allowing unlimited time and size to the account "typical account" I was testing with.
' olcLimits: dn.children="ou=accounts,dc=example,dc=com" time=unlimited size=unlimited '

Clearly the server is capable of serving data to the remote machine at 100Mbps (given that the rootDN has done so) 

I cannot for the life of me find a configuration option or setting would should be impacting the transmission bandwidth of searches. 
Any help or advice of where I should be looking would be greatly appreciated. 
I have included the relevant cn=config information below.

Thank you,
-Russell J. Jancewicz
University of Connecticut

OpenLDAP: slapd 2.4.36 (Sep 19 2013 11:16:48) $

dn: olcDatabase={1}mdb,cn=config
objectClass: olcDatabaseConfig
objectClass: olcMdbConfig
olcDatabase: mdb
olcDbDirectory: /srv/ldap/example.com
olcSuffix: dc=example,dc=com
# ... olcAccess 
olcLimits: {0}dn.exact="gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth" time=unlimited size=unlimited
olcLimits: {1}dn.children="ou=accounts,dc=example,dc=com" time=unlimited size=unlimited
olcRootDN: cn=root,dc=example,dc=com
olcDbCheckpoint: 512 30
olcDbNoSync: FALSE
olcDbMaxSize: 8589934592