Dear Rafaello, Are you using a local (preferably SSD-based) scratch drive, or a very fast parallel file system? Best wishes, Michal Krompiec Merck KGaA
On Wed, 30 Sep 2020 at 15:05, Raffaello Bianco < raffaello.bianco...@gmail.com> wrote: > Dear QE users and developers, > > I am doing an electron-phonon coupling calculation in this way (I am > using QE v 6.6). > First, I have done an scf calculation. Then, I have done a phonon > calculation where I have printed the dvscf files, with > > fildvscf = 'dvscf' > > Subsequently, I have done the electron-phonon calculation changing the > k-mesh grid, with > > trans = .false. > electron_phonon = 'simple' > > The calculation ends correctly, but for some q points I have noticed a > huge difference between > CPU and Wall time, like > > PHONON : 15h55m CPU 3d18h56m WALL > > From the report at the end of the output, the I/O davcio routine seems to > be the > "guilty": > > > General routines > davcio : 107.89s CPU 263856.08s WALL ( 520331 calls) > > Parallel routines > > Electron-phonon coupling > elphon : 41730.55s CPU 309708.87s WALL ( 1 calls) > elphel : 41671.20s CPU 309625.04s WALL ( 60 calls) > > General routines > davcio : 107.89s CPU 263856.08s WALL ( 520331 calls) > > This calculation was done with 10 processors and npool = 10, if I use 40 > processors and npool = 10 it is worse (as can probably be expected due to > the higher number of I / O operations). I have looked at the documentation > but I am not very familiar with these things, thus I still have several > doubts. Any suggestions on tests to do or how to improve performance, or at > least comments to clarify the problem, would be greatly appreciated. > > Thank you for your time, > > Best, > Raffaello Bianco > > > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > users mailing list users@lists.quantum-espresso.org > https://lists.quantum-espresso.org/mailman/listinfo/users
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