Set Tuning Parameters - Netscape DIRECTORY SERVER 6.0 Installation Manual

Operating System Requirements

Set Tuning Parameters

The transmission control blocks (TCBs) store data for each TCP connection. A
control block is attached to the TCB hash table for each active connection. If there
are not enough control blocks available when an LDAP connection arrives at the
server via TCP/IP, there is added delay while it waits for additional control blocks
to be created. By increasing the TCB timewait table size, you reduce latency
overhead by allowing more client connections to be serviced faster. To adjust this
value, add to the following registry key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters
the MaxFreeTcbs value of 0xFA0.
This example increases the TCB timewait table to 4,000 entries from the default of
2,000. Now that the overhead time introduced by TCP has been lowered for
Directory Server, adjust the corresponding hash table that stores the TCBs. Adjust
the hash table by adding to the following registry value:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters
the value of MaxHashTableSize to 0x400.
This increases the TCB hash table size from 512 to 1,024, allowing more room for
connection information. TCB information is stored in the nonpaged memory pool.
If Directory Server is experiencing memory bottlenecks and more memory cannot
be allotted to the server, lower the above values.
On a multiprocessor system, we recommend optimizing the NIC and CPU
relationship. Each LDAP request received over the network generates an interrupt
to the processor requesting service. If the processor does not consider the request to
be sufficiently urgent, (that is, with a sufficiently high interrupt level), it defers the
request. This deferred interrupt request becomes a Deferred Procedure Call (DPC).
As more and more requests come into the server, the number of interrupts and
DPCs increases.
When an interrupt is sent to a particular CPU and is subsequently deferred,
additional server overhead is incurred if this DPC is shipped off to another CPU in
the server (if the server is an SMP capable machine). This is NTs default behavior
and can be costly from a performance perspective. To stop this transfer from
happening, add to the following registry value:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NDIS\Parameters
the value of to .
ProcessorAffinityMask 0
Chapter 2 Computer System Requirements 37