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Message Posted: Wed, 28 Sep 2005 @ 17:04:25 GMT

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Subj:   Re: Priority scheduler question.
From:   Ballinger, Carrie

You can use either TOD milestones or cron jobs to alter priorities at different times of day. Both approaches work. The benefit of using the cron job approach are twofold:

1. You can change other parameters within a cron job, beyond just the allocation group association with a performance group (PG); for example, you could change a CPU limit at the resource partition level, or an allocation group (AG) policy.

2. If you choose to use TOD milestones on a performance group then you cannot also use query milestones, should you ever want to use them for that PG.

In your cron job syntax below, I would avoid changing the PG value when you change the AG association: In your 6:00 PM example you are giving H1H a value of 6, which at the time that command is issued that value is already being used by another PG (R1R) in the same resource partition, so I don't think that command will work for you. In general, you are better off not changing the values associated with PGs (values 0 and 1 are usually associated with the lowest priority PG, 6 and 7 with the highest)in your cron job.

Is your requirement really to switch PGs from one AG to another, or is the requirement more along the lines of changing the priority of work coming through that PG, which could mean not changing the PG at all, but just changing the characteristics of the AG it points to.

If you are using cron jobs it might be simpler to just change the assigned weights of the allocation groups, and leave the PG definitions alone:

     cron job at 6:00PM
     schmon -a 42 N DEF 40
     schmon -a 43 N DEF 20

     cron job at 12:00AM
     schmon -a 42 N DEF 20
     schmon -a 43 N DEF 40

But your PG approach will also work, if you keep the values consistent and just swap AGs:

     cron job at 6:00PM
     schmon -p 12 H1H  1 4 R 0 43
     schmon -p 13 H1H$ 1 5 R 0 43
     schmon -p 14 R1R  1 6 R 0 42
     schmon -p 15 R1R$ 1 7 R 0 42

     cron job at 12:00AM
     schmon -p 12 H1H  1 4 R 0 42
     schmon -p 13 H1H$ 1 5 R 0 42
     schmon -p 14 R1R  1 6 R 0 43
     schmon -p 15 R1R$ 1 7 R 0 43

Thanks, -Carrie

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