LAM: Maximum number of processes per node???

On Oct 8, 2007, at 11:57 AM, Ben Held wrote:
> I have a need to run around 100 processes per node on a
small Linux  
> cluster running LAM 7.1  I can only seem to run about
40 – after  
> that it just fails.  Although I have not seen an error
about too  
> many file descriptors, I did increase this limit by a
factor of 8  
> and no luck.
>
> Does LAM have a built in limit?  Can it be overridden?
>

Yes, there is a built-in limit.  We have not experimented
with making  
it larger, and the only way to override it is to change some
magic  
defines I can't recall at this time.  So overriding the
limit is both  
unsupported and not recommended.


Good luck,

Brian
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Brian Barrett wrote:
> On Oct 8, 2007, at 11:57 AM, Ben Held wrote:
>   
>> I have a need to run around 100 processes per node
on a small Linux  
>> cluster running LAM 7.1  I can only seem to run
about 40 – after  
>> that it just fails.  Although I have not seen an
error about too  
>> many file descriptors, I did increase this limit by
a factor of 8  
>> and no luck.
>>
>> Does LAM have a built in limit?  Can it be
overridden?
>>
>>     
>
> Yes, there is a built-in limit.  We have not
experimented with making  
> it larger, and the only way to override it is to change
some magic  
> defines I can't recall at this time.  So overriding the
limit is both  
> unsupported and not recommended.
>
>
> Good luck,
>
> Brian
> _______________________________________________
> This list is archived at http://www.l
am-mpi.org/MailArchives/lam/
>   

IIRC, the limit is in the lamd's management of its children.
 If so, 
might it be possible to "trick" lamboot into
starting multiple lamd's 
per node to circumvent this?

-Paul

-- 
Paul H. Hargrove                          PHHargrovelbl.gov
Future Technologies Group                 
HPC Research Department                   Tel:
+1-510-495-2352
Lawrence Berkeley National Laboratory     Fax:
+1-510-486-6900

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Brian,

What is the limit?  I have a problem that only fails when
run on 1024
processes, but I need to reproduce it on a system with only
12 nodes...

Thanks,

Ben

-----Original Message-----
From: lam-bounceslam-mpi.org [mailto:lam-bounceslam-mpi.org] On Behalf Of
Paul H. Hargrove
Sent: Monday, October 08, 2007 1:16 PM
To: General LAM/MPI mailing list
Subject: Re: LAM: Maximum number of processes per node???

Brian Barrett wrote:
> On Oct 8, 2007, at 11:57 AM, Ben Held wrote:
>   
>> I have a need to run around 100 processes per node
on a small Linux  
>> cluster running LAM 7.1  I can only seem to run
about 40 - after  
>> that it just fails.  Although I have not seen an
error about too  
>> many file descriptors, I did increase this limit by
a factor of 8  
>> and no luck.
>>
>> Does LAM have a built in limit?  Can it be
overridden?
>>
>>     
>
> Yes, there is a built-in limit.  We have not
experimented with making  
> it larger, and the only way to override it is to change
some magic  
> defines I can't recall at this time.  So overriding the
limit is both  
> unsupported and not recommended.
>
>
> Good luck,
>
> Brian
> _______________________________________________
> This list is archived at http://www.l
am-mpi.org/MailArchives/lam/
>   

IIRC, the limit is in the lamd's management of its children.
 If so, 
might it be possible to "trick" lamboot into
starting multiple lamd's 
per node to circumvent this?

-Paul

-- 
Paul H. Hargrove                          PHHargrovelbl.gov
Future Technologies Group                 
HPC Research Department                   Tel:
+1-510-495-2352
Lawrence Berkeley National Laboratory     Fax:
+1-510-486-6900

_______________________________________________
This list is archived at http://www.l
am-mpi.org/MailArchives/lam/

_______________________________________________
This list is archived at http://www.l
am-mpi.org/MailArchives/lam/

Hi Ben,

I had similar problem on Suse 10.1 and Fedora 4. On suse
10.2 the
problem disappear.

But you can overcome this.
1) boot you lam with "lamboot -v lamhost" where in
the lamhost you have
all nodes required
for example: if you need to simulate 100 nodes on one
physical cpu then
in lamhost you would have: localhost cpu=100
2) run your code with comand:
mpirun -ssi rpi crtcp C ./executabe

In may case with Lam MPI 7.1.2 it was OK. Let me know if it
works also
in your case.

Artur.

University of Czestochowa
Poland

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Artur,

Thanks - that worked.  However, I need to run across several
nodes (each
node with 100 processes).  Any thoughts?  Is this a OS issue
- I am running
Fedora Core 5 64-bit.

Ben

-----Original Message-----
From: lam-bounceslam-mpi.org [mailto:lam-bounceslam-mpi.org] On Behalf Of
Artur Tyliszczak
Sent: Monday, October 08, 2007 2:36 PM
To: General LAM/MPI mailing list
Subject: Re: LAM: Maximum number of processes per node???

Hi Ben,

I had similar problem on Suse 10.1 and Fedora 4. On suse
10.2 the
problem disappear.

But you can overcome this.
1) boot you lam with "lamboot -v lamhost" where in
the lamhost you have
all nodes required
for example: if you need to simulate 100 nodes on one
physical cpu then
in lamhost you would have: localhost cpu=100
2) run your code with comand:
mpirun -ssi rpi crtcp C ./executabe

In may case with Lam MPI 7.1.2 it was OK. Let me know if it
works also
in your case.

Artur.

University of Czestochowa
Poland

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