Technical data

Setting Up and Maintaining Queues
14.6 Using Queue Options
14.6.4.6 Options for Memory-Constrained Systems
On memory-constrained systems, total the pages required for the batch working
sets on all batch queues. Also make sure that enough fluid memory remains for
interactive jobs.
Fluid memory can be reassigned from one process to another through swapping
and paging. (You can calculate fluid memory as the space that remains when you
subtract the number of pages permanently allocated to the operating system from
the total memory. To obtain these values, enter SHOW MEMORY.)
14.6.4.7 Optimizing Batch Queues for the Sort/Merge Utility
You can improve the efficiency of the OpenVMS Sort/Merge utility
(SORT/MERGE) by designating one batch queue for sorting jobs and giving
this queue a very large working set quota.
You can also set process quotas for greatest SORT efficiency. The values
recommended here are based solely on SORT considerations; you should integrate
other system considerations with these to determine appropriate values.
• Working set extent per process (WSEXTENT system parameter)
For maximum sorting efficiency, use the /WSEXTENT qualifier with
INITIALIZE/QUEUE, START/QUEUE, or SET QUEUE to set this value
on the queue to the largest value any sorting job would ever need. Generally,
the smaller the working set, the slower the sort.
If you want to sort large files in batch mode, you need to set the WSEXTENT
system parameter to a large value to accommodate the sort.
• Virtual page count per process (VIRTUALPAGECNT system parameter)
For maximum sorting efficiency, set this system parameter to at least 1000
pages (on VAX systems) or pagelets (on Alpha systems) more than the
maximum working set extent. Although SORT limits the size of the sort
data structure to the process’s working set extent, if work files are required,
SORT can use the extra memory for I/O buffers. If this parameter is too low
relative to the working set extent, SORT might be unable to create buffers for
the work files when the files cannot be sorted in memory.
14.6.5 Specifying Job Scheduling Options
The queue manager uses the following criteria to determine the scheduling order
for batch and print jobs that are eligible for processing:
1. Job scheduling priority
The queue manager checks the job’s scheduling priority. The job with the
highest scheduling priority value is processed first. The job scheduling
priority is different than the base process priority or current process priority.
The user can specify job scheduling priority with the /PRIORITY qualifier of
the PRINT or SUBMIT command.
2. Size (optional, and applies only to output jobs)
By default, the job size of an output job is checked. Among jobs of identical
scheduling priority, the smallest job is processed first.
The job size is not checked if the queue has been created, started, or modified
to use the /SCHEDULE=NOSIZE option.
3. Submission time
Setting Up and Maintaining Queues 14–35