[mpich-discuss] where is two-phase I/O implemented

[Matthieu Dorier]

Thanks Rob. 
Good to know that it's the messiest part, I managed to find everything I need so I'm confident with the rest of ROMIO :)

Matthieu

----- Mail original -----
> De: "Rob Latham" <robl at mcs.anl.gov>
> À: discuss at mpich.org
> Envoyé: Lundi 6 Mai 2013 17:38:11
> Objet: Re: [mpich-discuss] where is two-phase I/O implemented
> 
> On Wed, May 01, 2013 at 11:41:52AM +0200, Matthieu Dorier wrote:
> > Btw how does Mpich knows which ADIO backend to use, in general?
> > (and
> > more specifically how does ADIOI_GEN_ReadStridedColl knows that it
> > has to use ADIOI_BGL_ReadContig?) Does it have something to do with
> > the fact that for instance with PVFS2 when the kernel module is not
> > used, the filename should be prefixed by pvfs2:// ? If I want to
> > develop a new ADIO backend, how can I make it such that filenames
> > prefixed with myfilesystem:// will use this backend? (Maybe there's
> > a documentation for that somewhere?)
> 
> To add a bit upon what Dries answered
> 
> Yes, if you prefix the file name, ROMIO will parse that and select
> the
> right set of function pointers.
> 
> ROMIO will also try to guess the file system type (usually with a
> 'statfs' call.)  See the functions in adio/common/ad_fstype.c.
> 
> It's a bit of a mess because on some platforms one calls statfs,
> others one calls fstatfs, etc.  If you squint around the preprocessor
> directives I hope it eventually makes sense.  Don't hesitate to ask
> me
> questions -- it's probably the messiest part of ROMIO ...
> 
> ==rob
> 
> > Thanks,
> > 
> > Matthieu
> > 
> > ----- Mail original -----
> > > De: "Pavan Balaji" <balaji at mcs.anl.gov>
> > > À: discuss at mpich.org
> > > Cc: "Matthieu Dorier" <matthieu.dorier at irisa.fr>
> > > Envoyé: Mardi 30 Avril 2013 18:01:11
> > > Objet: Re: [mpich-discuss] where is two-phase I/O implemented
> > > 
> > > 
> > > Please don't call it mpich3; it's just "mpich" :-).
> > > 
> > >  -- Pavan
> > > 
> > > On 04/30/2013 10:32 AM US Central Time, Matthieu Dorier wrote:
> > > > Hi,
> > > > 
> > > > A question more for the mpich3 developers:
> > > > 
> > > > If I were to implement an ADIO interface to a file system in
> > > > mpich3,
> > > > would I have to implement optimizations like two-phase I/O
> > > > myself
> > > > or are
> > > > these optimizations implemented outside ADIO, independently of
> > > > the
> > > > file
> > > > system?
> > > > 
> > > > Thanks,
> > > > 
> > > > Matthieu Dorier
> > > > PhD student at ENS Cachan Brittany and IRISA
> > > > http://people.irisa.fr/Matthieu.Dorier
> > > > 
> > > > 
> > > > _______________________________________________
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> > > 
> > > --
> > > Pavan Balaji
> > > http://www.mcs.anl.gov/~balaji
> > > 
> > _______________________________________________
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> 
> --
> Rob Latham
> Mathematics and Computer Science Division
> Argonne National Lab, IL USA
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