SNAX/XF LU Network Services Manual

Performance Consideration - ESS Table Allocation
Application Example
3–14 097841 Tandem Computers Incorporated
BEGIN
SELECTFILE $SYSTEM.SNAX.ESSTAB1, TYPE ESS, DEACTIVATE Y
ADD ESSCMD INVENTORY, &
CMDTYPE LOGON-CHAR, &
PROTOCOL CRT, &
PLUNAME #CREATE, &
CONCDATA ("PATHWAY", &
"NAME \SYS2.$PATHY ,", &
"PROGRAM INVENTORY")
DELETE HELP
ADD ESSMSG HELP, &
MSGTEXT (" ", &
%H85," PU:@@NDNAME.@@LNNAME.@@PUNAME ", &
%H85," LU:@@NDNAME.@@LNNAME.@@LUNAME ", &
%H85," TO ACCESS ENTER ", &
%H85," ---------- ----- ", &
%H85," TACL TACL ", &
%H85," ORDER ENTRY OE ", &
%H85," TSO TSO ", &
%H85," INVENTORY INVENTORY ", &
%H85," HOST HOST ", &
%H85," TANDEM TANDEM ", &
%H85," ", &
%H85," TO LOGOFF LOGOFF ")
END
ESS Table Allocation
and Performance
When an ESS table is needed for an LU during session establishment (SSCP—LU, or
LU—LU) or session termination (LU-LU), LUNS retrieves the table from a disk-
resident file. ESS tables are cached in extended segments in $SSCP address space. By
default, as many as 10 ESS tables may be resident at any given time (one in each of ten
different segments). If your configuration requires more than this default number, use
the SYSGEN attribute NUMSEGIDS to increase the number of available extended
segments to as many as 100. (For more information on the NUMSEGIDS attribute of
the SNAX/XF service manager, see the System Generation Manual for SNAX/XF.)
If a non-resident ESS table is needed and all available segments are already allocated,
the least frequently used segment is deallocated and a new segment is allocated for the
new ESS table. Actions such as these require a significant amount of time, because the
old file must be closed and the new one must be opened and read in. Therefore, a
system configured in such as way as to require a large number of ESS table allocations
and/or deallocation (multiple session establishments and/or termination requests) in
a short period of time can cause system performance to degrade ($SSCP slows down).