[Coin-discuss] SYMPHONY speedup

[Jack Bryan]

thanks

I have installed Blis-0.9  and try to run it on a cluster with MPICH2.
I am using 2 processes to run the benchmark  bell5.mps, which is a mixed 
integer linear programming. 

ftp://ftp.caam.rice.edu/pub/people/bixby/miplib/miplib3/bell5

I got error :

--------------------------------------
mpiexec -np 2 blis -par p0548.mps
Reading in ALPS parameters ...
Reading in BLIS parameters ...
Alps0110I ALPS version 1.0 (Parallel, MPI)
Alps0050I Launched 2 processes
Bcps0001I BiCePS version 0.9
Blis0001I BLIS version 0.9
Blis0020I WARNING: The Problem does not have integer variables
Fatal error in MPI_Barrier: Other MPI error, error stack:
MPI_Barrier(406)..........................: MPI_Barrier(MPI_COMM_WORLD) 

failed
MPIR_Barrier(77)..........................:
MPIC_Sendrecv(123)........................:
MPIC_Wait(270)............................:
MPIDI_CH3i_Progress_wait(215).............: an error occurred while 

handling an event returned by MPIDU_Sock_Wait()
MPIDI_CH3I_Progress_handle_sock_event(420):
MPIDU_Socki_handle_read(637)..............: connection failure 

(set=0,sock=1,errno=104:Connection reset by peer)[cli_1]: aborting job:
Fatal error in MPI_Barrier: Other MPI error, error stack:
MPI_Barrier(406)..........................: MPI_Barrier(MPI_COMM_WORLD) 

failed
MPIR_Barrier(77)..........................:
MPIC_Sendrecv(123)........................:
MPIC_Wait(270)............................:
MPIDI_CH3i_Progress_wait(215).............: an error occurred while 

handling an event returned by MPIDU_Sock_Wait()
MPIDI_CH3I_Progress_handle_sock_event(420):
MPIDU_Socki_handle_read(637)..............: connection failure 

(set=0,sock=1,errno=104:Connection reset by peer)
rank 0 in job 7  mountain.ece.college.edu_57166   caused collective abort 

of all ranks
  exit status of rank 0: killed by signal 11

--------------------------------------
Why Blis say that he Problem does not have integer variables ?
bell5 has 58 integer variables. 

Any help is appreciated. 

Jack
April 22 2009

> Date: Wed, 22 Apr 2009 10:16:48 +0200
> From: achterberg at zib.de
> To: dtustudy68 at hotmail.com
> CC: coin-discuss at list.coin-or.org
> Subject: Re: [Coin-discuss] SYMPHONY speedup
> 
> Hi Jack,
> 
> for MILP, your question cannot be answered (LP is a different story). Parallel speedup and
> performance difference accross different solvers depend on the model.
> 
> For example, there are models that can be solved by solver A in less than a second but
> that take forever by another solver B, just because solver B is lacking the important
> feature (like a cutting plane or a presolving reduction) to solve this particular model.
> And there may be other models for which the situation is reversed. Finally, there are
> models that can be solved in roughly the same time by all branch-and-cut MILP solvers.
> 
> Overall, my experience is that the algorithmic quality of a solver is usually much more
> important than parallelization. This means, that often solvers like CBC, SCIP, Gurobi,
> XPress, or CPLEX will be faster than Symphony, even if you use 1000 CPUs for Symphony.
> But, as I said, some models do not require the sophisticated machinery that these solvers
> provide and parallelize well. In this setting, Symphony can be really great if you have
> access to a massively parallel computing environment.
> 
> So, the short answer is: you just need to test it for your models. You cannot say in advance.
> 
> 
> Cheers,
> 
> Tobias
> 
> Jack Bryan wrote:
> > Hi ,
> > 
> > I am a new user of SYMPHONY .
> > 
> > I need to use it to solve very large mixed integer linear programming 
> > models.
> > 
> > So, I need to use PVM for SYMPHONY .
> > 
> > But, I do not know how much speed up I can get from the parallel SYMPHONY ?
> > 
> > For example, if it takes 100 seconds to solve a MILP model in CPLEX, how
> > long to solve it in SYMPHONY ?
> > 
> > 
> > thanks
> > 
> > Jack
> > 
> > April 21  2009
> > 
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