Re: Auto Tuning

The system has an Internal Time Slice of 500ms (milliseconds). If the time slice for a job is set to greater than 500ms, the system gives peer jobs of equal priority a chance to run.

For example, sbs=Subsystem, AL=Activity Level, TS=Time Slice in ms.

1 sbs BATCH1 AL=1 JobA TS=200
sbs BATCH2 AL=1 JobB TS=200
Processor runs each for 200ms and AL swaps equally.
2 sbs BATCH1 AL=1 JobA TS=200
sbs BATCH2 AL=1 JobB TS=2000
Processor trades jobs at 200ms and 500ms respectively.
3 sbs BATCH1 AL=1 JobA TS=500
sbs BATCH2 AL=2 JobB & JobC TS=200

- When JobA TS ends after 500ms, because it is the only job in the AL, processor handles it again after TS ends for
jobs B & C.

- If TS for JobB and JobC were 200ms, JobA would be handled again by the processor after running JobA for 200ms and JobB for 200ms, then JobA would run for 500ms.

- If the AL is set to greater than 500ms, the AL is held for that job after the processor tends to JobB and JobC for their respective TS limits. This means that after the internal TS limit is reached, the job does not lose its AL until its real TS is ended (assuming no Long Waits).

- Therefore, it is the AL that is more important than the TS in determining the effect of increasing the TS for a job and its affect on jobs in other or the same subsystem. Increasing the TS affects other jobs in the system to a minor extent only, because there is an internal 500ms limit. Adding more AL to a subsystem (with jobs to fill the levels) affects processor time for a job more than the increase of TS.

I would be surprised if the algorithm has changed to ignore the external
timeslice. I would not be surprised if this is another piece of
misinterpreted information passed on as fact - that seems to be how most
tuning stories go... Still, if you can find a source for this, I would
welcome the education.

Trevor