OSI/AS Configuration and Management Manual

Performance Considerations
OSI/AS Configuration and Management Manual—424119-001
6-5
MAXTAPS, MAXTSP, and MAXNSP Attributes
MAXTAPS, MAXTSP, and MAXNSP Attributes
The MAXTAPS, MAXTSP, and MAXNSP attributes specify the maximum number of
TAPS, TSP, and NSP processes that can be started in your OSI/AS subsystem. To
provide satisfactory throughput, you should define the appropriate number of processes
of each type, and then try to locate the processes in different CPUs. To maximize the
benefits of parallel processing, distribute your processes over multiple CPUs, to the
extent that it is practical on your system. You also need to consider other activities on
the system that might be competing for system resources. If you set the maximum
number of processes too high, or if the workload for the processes is too large, a CPU
may get overloaded, resulting in processing congestion.
Connection-Related Attributes
In addition to the PROCESS attributes, a number of other attributes relate to the
establishment of connections. Most of these values can be set in OSI/AS, which then
passes the values to OSI/TS, except where noted. These include:
•
LOOPBACK Attribute on this page
•
DELETETIME Attribute on this page
•
MULTIPLEX Attribute on page 6-6
•
CONNECTTIMEOUT Attribute on page 6-6
•
DISCONNECTTIMEOUT Attribute on page 6-6
•
CLASS Attribute on page 6-6
•
CIRCUITS and X25PORT Attributes on page 6-7
•
X25PVC Attribute on page 6-7
•
X25NCONMULTIPLEX Attribute on page 6-7
LOOPBACK Attribute
The LOOPBACK attribute allows connections having endpoints in the same subsystem
to run in loopback mode at the Session Layer. Because the calling end (the end that
issues a connect request) creates only a TAPS subdevice, the number of subdevices
created and closed for each loopback connection is reduced. This reduces the overhead
involved in setting up a new connection and increases the response time. Since a
loopback connection is handled entirely in a single TAPS process after the connection is
established (in other words, without a TSP process or NSP process or lower-layer
involvement), response time and throughput is improved, especially when the endpoints
are connected via an Expand network.
DELETETIME Attribute
The DELETETIME attribute specifies whether subdevices are deleted (dynamically
allocated) or saved (statically allocated) when a connection is terminated. The maximum
number of subdevices that can be open, whether in use or not, is determined by the
MAXCONNECTIONS attribute.
Static allocation of subdevices allows connections to be established faster, thus reducing
overhead, especially with applications that generate a large number of connections. You
should, however, make sure that your application specifies only existing subdevices.