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Re: [OT] Screen (was Affecting Inst. Change)



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On 05/12/07 02:51, william pursell wrote:
> Ron Johnson wrote:
> 
>> On 05/11/07 19:36, s. keeling wrote:
>>> Ron Johnson <ron.l.johnson@cox.net>:
>>>>  On 05/11/07 12:49, s. keeling wrote:
>>>>> Ron Johnson <ron.l.johnson@cox.net>:
> 
>>>>  How do you limit the number of batch jobs that can run at any one
>>>>  time?  (If the "job limit" of a queue is 4 and you submit 20 jobs,
>>>>  the first 4 jobs grab the execute slots, and the remaining 16 wait
>>>>  until execute slots open up.)
>>> Meaning, you'd prefer that all 16 jobs run concurrently?  That sounds
>>> sub-optimal (for most eventual users, at least).
>>
>> No.  Exactly the opposite.
>>
>> Think of a bank with 4 tellers.  If 20 people walk into the bank,
>> the first 4 get to the tellers, and the other 16 wait in the queue.
>>  As a customer at a teller finishes his business at a teller and
>> walks away, the next customer in line goes up to that teller.
> 
> I'm probably immersed too much in *nix, but I'm thinking, "Why?"
> If you have 20 jobs and 4 cpus, you schedule them all to run
> concurrently and you let the scheduler worry about the details
> of what runs.  If you really want to ensure that you don't
> take a hit for context switches, then you run them with a
> high absolute priority, via sched_setscheduler().  Most batch
> processing is I/O bound anyway, so this won't really have
> any impact.

That's the theory, anyway...

>             But, basically, it sounds like you want the
> batch manager to take over the job of the scheduler.  I
> don't see the advantage of that.

The "4 slot limit" was just an example.  Right now, we've got dozens
 of jobs running simultaneously.

- --
Ron Johnson, Jr.
Jefferson LA  USA

Give a man a fish, and he eats for a day.
Hit him with a fish, and he goes away for good!

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