Kbase P13854: What is the -spin parameter?
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
16/12/2003 |
|
Status: Unverified
GOAL:
What is the -spin parameter?
CAUSE:
P4635 How to tune -spin parameter
P10331 how to monitor ·spin parameter with promon
20208 How to Modify -spin parameter with a 4GL routine.
FIX:
On multi-processor systems, Progress uses a spin lock algorithm to control access to shared-memory structures and acquire the resource's latch. Spin lock ensure that only one process can use the structure at time, but that all process can get access to these structures quickly when they have to. When a process wants access to a resource, it tests the lock and finds it to be set by another process. The process tries to access the resource or ·spin· a specific number or times before it temporally ·rests·. The temporary rest is termed "latch timeout" and the number of retries before resting is controlled by the -spin parameter.
Tuning -spin essentially means increasing its value until the number of latch timeout no longer decreases. Increasing -spin will also cause an increase in cpu consumption, so you have to stop increasing it when CPU consumption gets above 90%.
A good rule to follow is to set the spin number at 1000 for every processor in the system.