Ref https://github.com/JuliaLang/julia/issues/12611#issuecomment-130902406
Further discussion should probably continue there. On Thu, Jul 30, 2015 at 9:38 PM, Deniz Yuret <[email protected]> wrote: > Here is a parallel program: > > M = [rand(1000,1000) for i=1:16] > @time pmap(svd, M) > > Here are timing results for local workers on a 16 core machine1: > > julia -p 2: 14.98 secs > julia -p 4: 16.02 secs > julia -p 8: 17.64 secs > > Here are timing results for machine1 connecting to remote workers on same > type of machine2: > > julia --machinefile <2 copies of machine2>: 11.75 secs > julia --machinefile <4 copies of machine2>: 7.54 secs > julia --machinefile <8 copies of machine2>: 6.46 secs > > At first I thought things got messed up if the master and the slaves were on > the same machine. > But it turns out the difference is between -p <n> vs. --machinefile. If I > rerun the same test on > a single machine, but use --machinefile instead of -p n: > > julia --machinefile <2 copies of machine1>: 8.41 secs > julia --machinefile <4 copies of machine1>: 4.70 secs > julia --machinefile <8 copies of machine1>: 3.31 secs > > I am using Julia Version 0.3.9 (2015-05-30 11:24 UTC). > > Why is -p n messed up? > > thanks, > deniz >
