[mpich-discuss] MPICH2 (or MPI_Init) limitation | scalability

[Darius Buntinas]

Great, I'm glad it worked.  BTW, the kernel.shmall et.al. parameters are used for System V shared memory, so they'll have no effect when using mmap-ed shared memory, which is how MPICH is configured by default.

-d

On Jan 12, 2012, at 5:31 AM, Bernard Chambon wrote:

> Hello,
> 
> Good news, It works !
> Whith your patch I can run 255 tasks and perhaps more, without any special
> configuration on the machine (*)
> 
> 
> It's a very good news for me,  Let me thank you very much Darius
> 
> >mpiexec -np 255 bin/advance_test 
> Running MPI version 2, subversion 2 
> I am the master task 0 sur ccwpge0062, for 254 slaves tasks, we will exchange a buffer of 10 MB
> 
> slave number 1, iteration = 1
> slave number 2, iteration = 1
> slave number 3, iteration = 1
> ...
> slave number 254, iteration = 1
> slave number 1, iteration = 2
> slave number 2, iteration = 2
> ...
> 
> slave number 254, iteration = 7
> 
> 
> Now will try to run jobs (thru GridEngine + Hydra) with higher numbers of tasks
> and I will tell you if it's ok
> 
> Best regards
> 
> 
> Le 11 janv. 2012 à 18:49, Darius Buntinas a écrit :
> 
>> I think I found the problem.  Apply this patch (using "patch -p0 < seg_sz.patch"), then "make clean; make; make install", and try it again.  Make sure to relink your application.
>> 
>> Let us know if this works.
>> 
>> Thanks,
>> -d
> 
> PS : 
> (*)
>  >limit
> cputime      unlimited
> filesize     unlimited
> datasize     unlimited
> stacksize    10240 kbytes
> coredumpsize unlimited
> memoryuse    unlimited
> vmemoryuse   unlimited
> descriptors  1024 
> memorylocked 32 kbytes
> maxproc      409600 
> 
>  >sysctl -A | egrep "shm"
> vm.hugetlb_shm_group = 0
> kernel.shmmni = 4096
> kernel.shmall = 2097152
> kernel.shmmax = 33554432
> 
> ---------------
> Bernard CHAMBON
> IN2P3 / CNRS
> 04 72 69 42 18
> 
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