[gmx-users] Slow Runs

Justin A. Lemkul jalemkul at vt.edu
Fri Jan 28 23:43:00 CET 2011



Denny Frost wrote:
> In the log file, when gromacs specifies "Nodes," does it mean processors?
> 

Yes.  For instance, on my dual-core workstation, the "nodes" are correctly 
reported as 2.

-Justin

> On Fri, Jan 28, 2011 at 1:44 PM, Justin A. Lemkul <jalemkul at vt.edu 
> <mailto:jalemkul at vt.edu>> wrote:
> 
> 
> 
>     Denny Frost wrote:
> 
>         I'm leaning toward the possibility that it is actually only
>         running 8 copies of the same job on different processors.  My
>         question is how does gromacs4.5 know how many processors it has
>         available to parallelize a job?  Is it specified in grompp or
>         does it just detect it?
> 
> 
>     If you're using MPI, it comes from mpiexec/mpirun/whatever.  Setting
>     a proper flag there is what tells mdrun how many nodes to use.
> 
>     -Justin
> 
>         On Fri, Jan 28, 2011 at 1:32 PM, Justin A. Lemkul
>         <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>> wrote:
> 
> 
> 
>            Denny Frost wrote:
> 
>                Here's my grompp command:
> 
>                grompp_d -nice 0 -v -f md.mdp -c ReadyForMD.gro -o md.tpr
>         -p top.top
> 
>                and my mdrun command is this:
>                time mpiexec mdrun_mpi -np 8 -cpt 30000 -nice 0 -nt 1 -s
>                $PBS_O_WORKDIR/md.tpr -o $PBS_O_WORKDIR/mdDone.trr -x
>                $PBS_O_WORKDIR/mdDone.xtc -c $PBS_O_WORKDIR/mdDone.gro -e
>                $PBS_O_WORKDIR/md.edr -g $PBS_O_WORKDIR/md.log 1>
>                $PBS_JOBID.pgm.out 4> $PBS_JOBID.pgm.err
> 
> 
>            The -np option of mdrun is nonexistent, but mdrun does not
>         check for
>            proper command line arguments, so you won't get an error.
>          But then
>            you've said that 8 processors are active, so I still suspect that
>            mdrun was compiled incorrectly or in such a way that it's
>            incompatible with your system.  The output from the .log file
>            indicates that only one processor was used.  Maybe your
>         admins can
>            help you on this one, if the jobs spit out any useful diagnostic
>            information.
> 
>            For our cluster, we use e.g.:
> 
>            mpirun -np 8 mdrun_mpi -deffnm md
> 
>            -Justin
> 
>                I know the -cpt option is 30000 because I don't want a
>                checkpoint file because every time it tries to make it,
>         it fails
>                due to quota issues and kills the job.  I'm not sure why this
>                happens, but I think it's a separate issue to take up with my
>                supercomputing facility.
> 
>                On Fri, Jan 28, 2011 at 1:18 PM, Justin A. Lemkul
>                <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>                <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>> wrote:
> 
> 
> 
>                   Denny Frost wrote:
> 
>                       all 8 nodes are running at full capacity, though
> 
> 
>                   What is your mdrun command line?  How did you compile it?
>                 What can
>                   happen is something went wrong during installation, so you
>                think you
>                   have an MPI-enabled binary, but it is simply executing 8
>                copies of
>                   the same job.
> 
>                   -Justin
> 
>                       On Fri, Jan 28, 2011 at 1:13 PM, Justin A. Lemkul
>                       <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>                <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>
>                       <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>                <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>>> wrote:
> 
> 
> 
>                          Denny Frost wrote:
> 
>                              Here's what I've got:
> 
>                              M E G A - F L O P S   A C C O U N T I N G
> 
>                                RF=Reaction-Field  FE=Free Energy
>                 SCFE=Soft-Core/Free
>                       Energy
>                                T=Tabulated        W3=SPC/TIP3p    W4=TIP4p
>                (single or
>                       pairs)
>                                NF=No Forces
> 
>                               Computing:                              
>         M-Number
>                                      M-Flops  % Flops
>                                          
>          -----------------------------------------------------------------------------
>                               Coul(T) + VdW(T)                  
>         1219164.751609
>                                 82903203.109    80.6
>                               Outer nonbonded loop                
>         25980.879385
>                                   259808.794     0.3
>                               Calc Weights                        
>         37138.271040
>                                  1336977.757     1.3
>                               Spread Q Bspline                  
>          792283.115520
>                                  1584566.231     1.5
>                               Gather F Bspline                  
>          792283.115520
>                                  4753698.693     4.6
>                               3D-FFT                            
>          119163.856212
>                                   953310.850     0.9
>                               Solve PME                            
>         2527.465668
>                                   161757.803     0.2
>                               NS-Pairs                            
>         47774.705001
>                                  1003268.805     1.0
>                               Reset In Box                          
>         371.386080
>                                     1114.158     0.0
>                               Shift-X                            
>          24758.847360
>                                   148553.084     0.1
>                               CG-CoM                              
>          1237.953600
>                                     3713.861     0.0
>                               Angles                              
>         18569.135520
>                                  3119614.767     3.0
>                               Propers                            
>          14855.308416
>                                  3401865.627     3.3
>                               Impropers                            
>         3094.855920
>                                   643730.031     0.6
>                               Virial                              
>          1242.417375
>                                    22363.513     0.0
>                               Stop-CM                              
>         1237.953600
>                                    12379.536     0.0
>                               P-Coupling                          
>         12379.423680
>                                    74276.542     0.1
>                               Calc-Ekin                          
>          12379.436160
>                                   334244.776     0.3
>                               Lincs                              
>          11760.476208
>                                   705628.572     0.7
>                               Lincs-Mat                          
>         245113.083072
>                                   980452.332     1.0
>                               Constraint-V                        
>         23520.928704
>                                   188167.430     0.2
>                               Constraint-Vir                      
>         11760.452496
>                                   282250.860     0.3
>                                          
>          -----------------------------------------------------------------------------
>                               Total                                    
>                                        102874947.133   100.0
>                                          
>          -----------------------------------------------------------------------------
> 
> 
>                                  R E A L   C Y C L E   A N D   T I M E  
>         A C C
>                O U N T
>                       I N G
> 
>                               Computing:         Nodes     Number    
>         G-Cycles
>                          Seconds     %
>                                          
>          -----------------------------------------------------------------------
>                               Neighbor search    1      99195    
>         8779.027            3300.3
>                             3.8
>                               Force                   1     991941  
>         188562.885
>                          70886.8           81.7
>                               PME mesh           1     991941  
>          18012.830            6771.6
>                            7.8
>                               Write traj.             1            41  
>                  16.835                 6.3
>                                       0.0
>                               Update                 1     991941    
>         2272.379
>                            854.3              1.0
>                               Constraints           1     991941  
>          11121.146                   4180.8     4.8
>                               Rest                     1                
>                   2162.628                    813.0      0.9
>                                          
>          -----------------------------------------------------------------------
>                               Total                    1                
>                 230927.730                  86813.1   100.0
>                                          
>          -----------------------------------------------------------------------
>                                          
>          -----------------------------------------------------------------------
>                               PME spread/gather      1    1983882      
>               17065.384           6415.4   7.4
>                               PME 3D-FFT               1    1983882    
>                 503.340              189.2
>                                  0.2
>                               PME solve                  1     991941  
>                    427.136                     160.6     0.2
>                                          
>          -----------------------------------------------------------------------
> 
>                              Does that mean it's only using 1 node?
>          That would
>                       explain the
>                              speed issues.
> 
> 
>                          That's what it looks like to me.
> 
> 
>                          -Justin
> 
>                          --     ========================================
> 
>                          Justin A. Lemkul
>                          Ph.D. Candidate
>                          ICTAS Doctoral Scholar
>                          MILES-IGERT Trainee
>                          Department of Biochemistry
>                          Virginia Tech
>                          Blacksburg, VA
>                          jalemkul[at]vt.edu <http://vt.edu>
>         <http://vt.edu> <http://vt.edu>
>                <http://vt.edu> | (540)
> 
>                       231-9080
> 
>                        
>          http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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>                   --     ========================================
> 
>                   Justin A. Lemkul
>                   Ph.D. Candidate
>                   ICTAS Doctoral Scholar
>                   MILES-IGERT Trainee
>                   Department of Biochemistry
>                   Virginia Tech
>                   Blacksburg, VA
>                   jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu>
>         <http://vt.edu> | (540)
>                231-9080
>                   http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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>            --     ========================================
> 
>            Justin A. Lemkul
>            Ph.D. Candidate
>            ICTAS Doctoral Scholar
>            MILES-IGERT Trainee
>            Department of Biochemistry
>            Virginia Tech
>            Blacksburg, VA
>            jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu> | (540)
>         231-9080
>            http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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>     -- 
>     ========================================
> 
>     Justin A. Lemkul
>     Ph.D. Candidate
>     ICTAS Doctoral Scholar
>     MILES-IGERT Trainee
>     Department of Biochemistry
>     Virginia Tech
>     Blacksburg, VA
>     jalemkul[at]vt.edu <http://vt.edu> | (540) 231-9080
>     http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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-- 
========================================

Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
MILES-IGERT Trainee
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

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