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Re: [Condor-users] PROBLEMS WITH HYPER THREADING
- Date: Sat, 14 Jun 2008 17:10:12 -0300 (ART)
- From: Paula Martinez <pmart@xxxxxxxxxxx>
- Subject: Re: [Condor-users] PROBLEMS WITH HYPER THREADING
Thanks again, the problem is when I run 1,800 iterations, there, when I
submit my job it takes 2 hrs without constrains, then I say "just VM1" and
it takes the same time!, but if I run 3 iterations when I submit the job,
without constrains it takes half the time that if I put just vm1.
Remember that the executable is not paralellized.
The Condor_status doesn't show owner, juste climed, unclimed or idle.
If the job is not paralellized Condor won't benefit of hyperthreaded cores?
Thanks a lot
>> Hi Ian, thank you so much! yes it makes sense!, but I wasn't clear.
>> I've a cluster with 12 P4 HT 3 GHz. Then I submit my job that
>> has queue 40, and each time must make 1,800 runs (its a
>> genetic algorithm). It is not paralellized.
> Ahh! That clears things up thanks.
>> When I submit my job it takes 2 hrs without constrains, then
>> I say "just VM1" and it takes the same time.
>> In the machines I've put (is this config.ok?):
>> NUM_CPUS = 2
>> NUM_VIRTUAL_MACHINES_TYPE_1= 2
> Are you defining custom virtual machine types? If you're not creating
> custom virtual machines you can comment the line above
> (NUM_VIRTUAL_MACHINES_TYPE_1) out.
>> NUM_VIRTUAL_MACHINES = 2
>> VIRTUAL_MACHINES_CONNECTED_TO_CONSOLE = 2
>> VIRTUAL_MACHINES_CONNECTED_TO_KEYBOARD = 2
>> COUNT_HYPERTHREAD_CPUS = TRUE
> It won't matter what you set COUNT_HYPERTHREAD_CPUS to because you're
> overriding Condor's "take a guess at how many CPUs there are" mechanism
> when you explcitly set NUM_CPUS and NUM_VIRTUAL_MACHINES.
>> Then I tried to run with queue
>> 40, but each job with 3 runs(not 1,800) just to obtain results faster.
> Got it. I'm understanding what you're doing now. Job lands on a machine:
> does 3 itterations of your algorithm in serial. Right?
>> In this scenario, if I submit the job, without constrains it
>> takes half the time that if I put just vm1, for example.
> This makes sense. If you have 12 machines each with two slots and you
> constrain your jobs to only run on slot 1 you you'll run 12 instances of
> your algorithm in parallel. But if you omit the slot constraint you'll
> run 24 instances of your algorithm in parallel so your jobs will run
> roughly twice as fast (assuming all things are equally w.r.t. your
> But: this is different from what you wrote in the first paragraph of
> this post. In your first paragraph you make it sound like with or
> without a slot constraint the same number of jobs, running the same
> number of algorithm itterations per job, takes the same amount of time.
> Is this the problem?
>> The executable is the same, so I don't know why is beheaving
>> like that.
> One possibility might be that only 1/2 the slots on your machines are
> available to run jobs because the other half are in the owner state.
> What does condor_status show for your pool?
> - Ian
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Ing. Paula Martinez
ITU - Redes y Telecomunicaciones