Pathway/iTS System Management Manual (G06.24+)

Tuning Your System Using Statistics
HP NonStop Pathway/iTS System Management Manual—426748-002
5-21
I/O Info
require a physical I/O operation, REQ CNT indicates the number of logical I/O
operations—not the number of physical I/O operations.
The DISPLAY statements generally cause the TCP to generate data for the terminal
and place the data in a TERMPOOL buffer, but do not always require that the TCP
write the buffer to the terminal. Consequently, a logical I/O operation does not
necessarily generate a physical I/O operation.
When the TCP receives a request to write the buffer to a terminal, DISPLAY I/O CNT is
incremented by 1.
In general, the number of logical I/O operations (indicated by REQ CNT) should be
greater than the number of physical I/O operations (indicated by I/O CNT). (This is not
true for IDS, however.) If the number of logical I/O operations is not greater, you should
check for the following:
•
The buffer might be too small.
•
The TCP requester might be coded with a delay or other statements that cause the
TCP to perform two-part I/O operations.
If more than one I/O is required, you might want to examine the requester code.
MAX TSIZE
MAX TSIZE indicates the size of the largest data transfer for the DISPLAY, ACCEPT,
SEND, and REPLY statements and for checkpoint operations. To set MAX TSIZE, ask
your application developers for the value of the largest amount of data that could be
transferred from a server.
DISPLAY Statements
For DISPLAY, MAX TSIZE indicates the size of the largest amount of data sent to the
terminal.
If the number indicated for MAX TSIZE is greater than that specified for TERMBUF,
multiple I/O operations are required to display the data. To reduce the number of I/O
operations required to display the data, you should:
•
Increase the size of TERMBUF (using the SET TCP TERMBUF command) to
MAXTSIZE +8.
•
Increase the size of TERMPOOL (using the SET TCP TERMPOOL command) by
the corresponding amount.
REPLY
For REPLY, MAXTSIZE indicates the largest amount of data transferred from a server.
To determine the most efficient value for the SET TCP MAXREPLY command, use the
value indicated for MAXTSIZE.