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Justin A. Lemkul wrote:
<blockquote cite="mid:49833017.7050606@vt.edu" type="cite"><br>
<br>
Dimitris Dellis wrote:
<br>
<blockquote type="cite">Hi.
<br>
I run the same (exactly) simulations with v3.3.3 and v4.0.3, on the
same 64bit Q6600/DDR2-1066 machine, gcc-4.3.2 ,fftw-3.2.
<br>
I found that the performance of 4.0.3 is roughly 30% lower than 3.3.3
(30% higher hours/ns), for few systems (512 molecules of 5-15 sites,
nstlist=10) I tried.
<br>
This happens with single precision serial and parallel, np=2,4
(openmpi 1.3) versions and only when electrostatics (PME) are present.
<br>
With Simple LJ potentials the performance is exactly the same.
<br>
Is there any speed comparison 3.3.3 vs 4.0.3 available ?
<br>
D.D.
<br>
<br>
</blockquote>
<br>
Can you show us your .mdp file? What did grompp report about the
relative PME load? These topics have been discussed a few times;
you'll find lots of pointers on optimizing performance in the list
archive.
<br>
<br>
-Justin
<br>
<br>
</blockquote>
<tt>Hi Justin,<br>
These are from the small system, no I/O only 1k steps.<br>
grompp.mdp<br>
===========<br>
integrator = md<br>
dt = 0.0010<br>
nsteps = 1000<br>
nstxout = 0<br>
nstvout = 0<br>
nstlog = 1000<br>
nstcomm = 10<br>
nstenergy = 0<br>
nstxtcout = 0<br>
nstlist = 10<br>
ns_type = grid<br>
dispcorr = AllEnerPres<br>
tcoupl = berendsen<br>
tc-grps = System<br>
ref_t = 293.15<br>
gen_temp = 293.15<br>
tau_t = 0.2 <br>
gen_vel = no<br>
gen_seed = 123456<br>
constraints = none<br>
constraint_algorithm = shake<br>
dispcorr = AllEnerPres<br>
energygrps = System <br>
rlist = 1.6<br>
vdw-type = Cut-off<br>
rvdw = 1.6<br>
coulombtype = PME<br>
fourierspacing = 0.12<br>
pme_order = 4<br>
ewald_rtol = 1.0e-5<br>
optimize_fft = yes <br>
rcoulomb = 1.6<br>
<br>
related 4.0.3 grompp output<br>
Estimate for the relative computational load of the PME mesh part: 0.19<br>
</tt><br>
<tt>4.0.3 mdrun serial timings (near zero omitted)</tt><br>
<tt><br>
Coul(T) + LJ 576.513824 31708.260 71.5<br>
Outer nonbonded loop 8.489390 84.894 0.2<br>
Calc Weights 6.006000 216.216 0.5<br>
Spread Q Bspline 128.128000 256.256 0.6<br>
Gather F Bspline 128.128000 1537.536 3.5<br>
3D-FFT 1088.769682 8710.157 19.6<br>
Solve PME 18.531513 1186.017 2.7<br>
<br>
parallel 4.0.3 np=4 <br>
Average load imbalance: 5.2 %<br>
Part of the total run time spent waiting due to load imbalance: 2.3 %<br>
Performance: 96.086 7.380 14.414 1.665<br>
<br>
3.3.3 mdrun serial timings</tt><br>
<tt>Coul(T) + LJ 576.529632 31709.129760 72.0<br>
Outer nonbonded loop 8.487860 84.878600 0.2<br>
Spread Q Bspline 128.128000 256.256000 0.6<br>
Gather F Bspline 128.128000 1537.536000 3.5<br>
3D-FFT 1088.769682 8710.157456 19.8<br>
Solve PME 17.986469 1151.133984 2.6</tt><br>
<tt><br>
parallel 3.3.3 np=4<br>
Performance: 144.132 12.556 21.600 1.111</tt><br>
<br>
D.D.<br>
<br>
<blockquote cite="mid:49833017.7050606@vt.edu" type="cite">
<blockquote type="cite"><br>
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