[GE users] Questions on functional policy, share tree policy, and priority queue

Reuti reuti at staff.uni-marburg.de
Fri May 23 12:26:20 BST 2008


Am 21.05.2008 um 02:29 schrieb Steve Chapel:

> Hi,
>
> I'm new to Sun Grid Engine. I have it set up on a small Rocks cluster
> running SGE 6.0 for the three owners of the company I work for, but  
> want a
> more fair scheduling policy than the default FIFO policy. I want to  
> ensure
> that all three owners get approximately equal access to the  
> cluster. All
> jobs are single batch jobs or array batch jobs, in an embarrassingly
> parallel situation. Each of the compute nodes has two quad-core  
> processors.
>
> In particular, I want to ensure the following:
> 1. If there is no contention for CPUs, a user should get access to  
> as many
> CPUs as they need (equal to either the number of jobs they have run  
> or the
> number of CPUs, whichever is less).
> 2. If two or more users need to compete for CPUs, they should each  
> get a
> "fair share" of CPU time.
> 3. In case of urgent need, we should be able to run jobs that will  
> preempt
> any currently running jobs.
>
> It seems to me that I want to set up either a functional policy or  
> a share
> tree policy. In addition, I want a queue that supersedes the  
> default all.q.
> I have read through the documentation, and it looks like this is  
> what I
> should set up:
> * Add high-priority queue: qconf -aq priority.q
> * Add all.q to priority.q subordinate list: qconf -mattr queue
> subordinate_list all.q priority.q
> * Set priority of priority.q to highest: qconf -mattr queue  
> priority -20
> priority.q
> * In conf, set auto_user_fshare to 100
> * Check that fshare is 100 for all users listed in qconf -suserl
> * In sconf, set halftime to 48, compensation_factor to 5
> * Add stree: id=0, name=default, type=0, shares=100, childnodes=NONE
> * For functional policy: in sconf, set weight_tickets_functional to  
> 10000,
> weight_tickets_share to 0
> * For share tree policy: in sconf, set weight_tickets_functional to 0,
> weight_tickets_share to 10000
>
> Some specific questions I have on these settings are:
> 1. Is there a possibility that a user may not be able to use all  
> available
> CPUs on the cluster if there are enough jobs to use all CPUs?

You will need to setup RQS to define it per user:

http://gridengine.sunsource.net/nonav/source/browse/~checkout~/ 
gridengine/doc/devel/rfe/ResourceQuotaSpecification.html

> 2. Will the functional and share tree policy settings not interfere  
> with
> each other as long as either weight_tickets_functional or
> weight_tickets_share are 0?

You could even set in the scheduler config, to use only one of the  
two in "policy_hierarchy" and leave one out.

> 3. Will submitting jobs to priority.q always immediately cause at  
> least some
> currently running jobs to be suspended? Will it cause all currently  
> running

Well, in your setup the all.q instance on a node will be suspended  
when *all* slots of priority.q are filled on a particular machine.  
You could setup:

all.q=1

and as soon as one slot is used in priority.q the complete queue  
instance on this machine is suspended. Possibly blocking 7 other  
jobs. It's not implemented for now to suspend slots instead of  
complete queue instances. What I would suggest: fill the cluster from  
the one side with all.q, and from the other with priority.q to  
minimize the effect by using sequence numbers and setting up the  
scheduler to sort queus by seqno instead of load.

> jobs to be suspended if a user submits enough jobs?
> 4. Does setting the -20 priority of priority.q have an effect?

Don't do this! Nice values below zero are reserved for system tasks!  
For user jobs only use 0 (high) to 19 (low).

-- Reuti


> 5. Are there any settings I have missed?
>
> Thanks,
> Steve
>
>
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