[GE users] Memory quotas

davidecittaro davide.cittaro at ifom-ieo-campus.it
Tue Feb 10 11:09:53 GMT 2009


Hi Reuti

On Feb 10, 2009, at 11:58 AM, reuti wrote:
>
>
> the difference is, that h_vmem is enforced, while virtual_free is
> just a guidance for SGE; as long as the users are fair and know what
> their jobs consume. With h_vmem some jobs might crash, when they need
> just one byte more. But over time these requests can be adjusted.
>

Ok, I see... and should it be set as complex value in execution host  
configuration?

>>
>> $ qconf -srqs MemoryQuota
>> {
>>    name         MemoryQuota
>>    description  Memory quota for users. Nobody can use more than 30
>> Gb RAM
>>    enabled      TRUE
>>    limit        users {*}  to virtual_free=30G
>> }
>
> But this is per user, not per host or job (i.e. slot). You have one
> big SMP machine or a cluster of nodes?
>

Yes, this is the case. There are only a couple of users (including me)  
that really use a lot of memory. We have 64 Gb RAM nodes (and 24  
processors each)....
Talking about this, I've noticed that if a user sends qlogin, qquota  
says that he is using 5 Gb RAM (I'm using qlogin_wrapper to sshd). I  
wonder why this is happening...



>> This, at least, allows me to keep jobs in qw state until the quota is
>> exceeded. Good. Also, since virtual_free is a load sensor it is
>> reported to the quota even if it is not requested. Plus, if a user
>> specifies -l virtual_free=X, his remaining quota is lowered by X.
>> This seems to be a fair solution but I have some issues I suspect are
>> not easy to solve:
>> - How can I handle users that run jobs that exceed quota while they
>> are running? I mean, if an user submits a job that at a certain point
>> allocates for 50 Gb, it drains lot of the memory available
>
> Use h_vmem and these jobs will be killed. And you could specify
> h_vmem as FORCED in the consumable configuration and/or set a high
> default value (and user could lower them). You you implement this, it
> could be useful to enable reservation in the scheduler and request
> reservation with "-R y" in your qsub request.
>

Just a doubt: suppose I set h_vmem to 40 Gb, will a job be killed if  
it goes over 40 Gb or every job is killed as the 40 Gb is reached?


>> - I cannot set a suspend threshold for memory, as the memory
>> referenced by a process can't be lowered while it is running (isn't
>> it?)
>
> Correct. Also suspended jobs occupy resources they got granted.

Yes, of course, but at least the load decreases :-) (I have suspend  
thresholds only for load sensors)

thanks again

d

Davide Cittaro
davide.cittaro at ifom-ieo-campus.it

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