cpu accounting flush interval

cpu accounting flush interval specifies the amount of time, in machine clock ticks (non-SAP ASE clock ticks), that SAP ASE waits before flushing CPU usage statistics for each user from sysprocesses to syslogins, a procedure used in charge-back accounting.

When a user logs in to SAP ASE, the server begins accumulating figures for CPU usage for that user process in sysprocesses. When a user logs off SAP ASE, or when the value of cpu accounting flush interval is exceeded, the accumulated CPU usage statistics are flushed from sysprocesses to syslogins. These statistics continue accumulating in syslogins until you clear the totals. Display the current totals from syslogins using sp_reportstats.

The value to which you set cpu accounting flush interval depends on the type of reporting you intend to do. If you run reports on a monthly basis, set cpu accounting flush interval to a relatively high value. With infrequent reporting, it is less critical that the data in syslogins be updated frequently.

However, if you perform periodic ad hoc selects on the totcpu column in syslogins to determine CPU usage by process, set cpu accounting flush interval to a lower value to increase the likelihood of the data in syslogins being up-to-date when you execute your selects.

Setting cpu accounting flush interval to a low value may cause the lock manager to mistakenly identify processes as potential deadlock victims. When the lock manager detects a deadlock, it checks the amount of CPU time accumulated by each competing processes. The process with the lesser amount is chosen as the deadlock victim and is terminated by the lock manager. Additionally, when cpu accounting flush interval is set to a low value, the task handlers that store CPU usage information for processes are initialized more frequently, thus making processes appear as if they have accumulated less CPU time than they actually have. Because of this, the lock manager may select a process as the deadlock victim when, in fact, that process has more accumulated CPU time than the competing process.

If you do not intend to report on CPU usage at all, set cpu accounting flush interval to its maximum value. This reduces the number of times syslogins is updated, and reduces the number of times its pages must be written to disk.