Within the two most common priority classes-time-critical and regular-there are certain broad guidelines recommended for choosing the priority level for a program.
The guidelines for level within the time critical class are set to maximize the number of different applications that can successfully multitask in an OS/2 system. The guidelines are described in the following table.
Recommended Priority Levels for Time-Critical Threads
旼컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴커 쿌ctivity 쿝ange of Recommended쿕ustification/Comments � � 쿛riority Levels � � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴캑 쿝obotics/Real time �20-31 쿚S/2 systems can be used on manufacturing lines to control � 쿾rocess control � 쿮quipment or in other real time process control � � � 쿪pplications. In this case a slow response from the PC could� � � 쿬ause expensive damage to equipment or even human injury. � � � 쿟herefore the highest priority levels should be reserved for� � � 퀃hese applications. � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴캑 쿎ommunications �10-19 쿔n communications, the inability to get the processor could � � � 쿬ause a loss of data or communications sessions. Therefore � � � 퀃his class of applications is next highest. � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴캑 쿚ther �0-09 쿚ther threads might need to preempt the foreground in � � � 퀂pecial cases (for example, Control-Break). These should be � � � 퀂et below the other 2 classes. � 읕컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴켸
In general, application performance is not a good reason to make a thread time critical.
In cases where explicit priority levels are set, they should follow the guidelines listed below.
Recommended Priority Levels for Regular Priority Threads
旼컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴커 쿌ctivity 쿝ange of Recommended쿕ustification � � 쿛riority Level � � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴캑 쿎ommunications �26-31 쿎ommunications should take priority over other � � � 쿫ackground processing to increase overlap with � � � 퀃ransmission and processing on the partner PC or � � � 쿴ost. This gives the best system performance. � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴캑 쿚ther �0-25. 쿔f an application has multiple threads it might be� � � 쿻ecessary to set them to several different � � � 쿾riorities to optimize the order in which they � � � 퀁un. A range of priority levels is provided to � � � 쿯acilitate this. (The default priority is regular � � � 쿬lass, level = 0.) � 읕컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴켸