Kbase 16518: The functionality of (-napmax) and (-spin) parameters
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/16/2008 |
|
Status: Unverified
GOAL:
The functionality of (-napmax) and (-spin) parameters
FIX:
In Progress, shared memory resources are controlled by utilizing a spin lock algorithm. If a process needs a shared memory resource the process is required to obtain the resource's latch. If that latch cannot be used because it is in use by another process it will continue to try to grab the latch. This procedure of
repeatedly trying to obtain the latch is called SPINNING. The number of times this procedure will take place is determined by the (-spin) parameter.
The (-spin) parameter sets the number of attemps a process will make when trying to grab a latch.
For dual- or multi- processor machines the -spin parameter can be initially configured to 2000. There are no other parameters that help the optimal performance of multi CPU machines.
If the process is unable to obtain the latch after spinning it will stop or (nap). (The nap time is measured in milliseconds) After the process pauses, to release cpu time, it will begin the spin process again. This process will be repeated until the latch is obtained. If this process is unsuccessful the nap time will gradually increase with each iteration.
In version 6.3, the napmax time had a default time of 10, 20, 40, 80, 160... up to 5000. Beginning in version 7.3C the napmax time is sequenced so that with each iteration it will go from 20, 40, 80, and then to a variable limit of 100 milliseconds. Each additional nap will then default and continue at 100 milliseconds. This 100 millisecond limit can now be increased (up to 5000 if needed). You can adjust this variable limit by increasing the (-napmax) parameter to the desired length of time.
On version 9 you can set the nap interval (-nap) and the maximum nap interval (-napmax) using Progress Explorer. You will find these parameteres under Defaultconfiguration properties, Advanced, Lock Delay session. Nap interval corresponds to the parameter -nap and Nap maximum interval corresponds to the parameter -napmax.