[Pvfs2-developers] Hints in pvfs2

[Sam Lang]

Hi Christina,

With our latest releases 2.8.*, PVFS has generic hint fields that can  
be passed through from end-to-end.  All of the PVFS system interface  
calls on the client now take a PVFS_hint parameter.  This can actually  
be a list of hints.  Once a hint is passed into a PVFS_sys_* call, it  
will be handed around to the different components that take part in  
that call, including being sent around to the servers.

To construct pre-defined hints or create your own, have a look at  
include/pvfs2-hint.h.    The pre-defined hints are listed at the top  
of that file.  You can define a bunch of hints easily by doing  
something like:

int myid = 100;
PVFS_hint ph = PVFS_HINT_NULL;

PVFS_hint_add(
	&ph,
	"me.hints.myhint",
	sizeof(myid),
	&myid);

Other hints you define can be added to the same ph variable in the  
same fashion.  Once you have the hints you want, you can just pass  
that ph variable to the PVFS_sys_* calls.

To access the hints you've added within PVFS, have a look at src/ 
common/misc/pint-hint.h.  Especially PINT_hint_get_value_by_name.

That should get you started.
-sam


On Mar 3, 2009, at 9:18 PM, Christina Patrick wrote:

> Hi Everybody,
>
> I have some questions to ask regarding the implementation of hints  
> in PVFS2.
>
> Like the file "src/mpi/romio/adio/include/adioi.h" in the mpich2 src
> tree, is there any similar file in the pvfs2 src tree which has a hint
> structure. Basically, I want to know if there is any generic hint
> structure in pvfs2 which can take care of (accept) hints passed by
> higher layers such as MPI, and if so, which files? (whether pvfs2 acts
> on it or not does not matter) I want to know if such an infrastructure
> exists already?
>
> I was just browsing through the pvfs2 code and I found that there is
> some PINT_hint_info structure. Is this a generic hint structure or is
> this related to some specific component in pvfs2? (I understand that
> there are more than one hint structures in pvfs2 such as related to
> metadata)
>
> Is there any documenation on hints in pvfs2 (docs, papers) where I
> could read about it? I am not familiar with the pvfs2 src code and
> would really appreciate all the help that I could get from you'll.
>
> Thanks and Regards,
> Christina.
> _______________________________________________
> Pvfs2-developers mailing list
> Pvfs2-developers at beowulf-underground.org
> http://www.beowulf-underground.org/mailman/listinfo/pvfs2-developers