[Pw_forum] EXX files I/O

[Stefano de Gironcoli]

Thank'you for noticing that... it will be changed.
a simple temporary fix  is to move the opening of the exx files into 
openfil.f90

#ifdef EXX
     exx_nwordwfc=2*nrxxs
     iunexx = find_free_unit()
     call diropn(iunexx,'exx', exx_nwordwfc, exst)
#endif

in this way they will be open in the same directory as wfc## files.
Thank you,

stefano de Gironcoli,
SISSA and DEMOCRITOS

On Sat, 18 Aug 2007, Tyler Grassman wrote:

> Hello.  I've been working with the EXX implementation in PWscf for a little
> bit now (just doing testing on bulk Si for the time being, getting to know
> the code a little bit, as I'm new to PWscf).  I'm working on figuring out
> the optimal parallelization and disk I/O parameters.  My cluster uses an NSF
> file system to share the /home directory (I know, everyone says not to with
> PWscf, but I don't see that I've much other choice).  However, the compute
> nodes have large scratch disks, so setting the wfcdir tag to use the local
> node scratch disks helps reduce the NFS disk I/O.  However, I find that the
> prefix.exx# files are still being written to the outdir, and they tend to be
> pretty big (each file is tens to hundreds of MBs, depending on the number of
> procs the job is being run on, even for this small bulk system).  It looks
> like these files get rewritten every hybrid refinement loop (i.e. "NOW GO
> BACK TO REFINE HYBRID CALCULATION").  I'm guessing these files will get
> considerably larger once the system gets larger, too, in which case this I/O
> will really end up costing a lot in the wall time (and I plan on trying some
> considerably larger systems in the near future), yes?  I looked in input.f90
> source file and didn't see anything about it, but I was wondering if there
> was any way (or a plan to implement such a thing, if possible) to treat
> these files in the same way (some equivalent to wfcdir)?  Or if not, does
> anyone have any suggestions?
>
> Thanks,
>
> Tyler Grassman
> Materials Science and Engineering
> University of California, San Diego
>
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