I think that technically, the component can do whatever it wants
(e.g., look at its priority, see 0, and decide to return NULL).
However, to be consistent, we should decide on a specific behavior and
make it uniform to all components.
I'd opt for the ^foo notation to disable a component.
On May 23, 2008, at 8:14 AM, Rolf Vandevaart wrote:
This mostly makes sense. But let me probe a little more. Can a
component return NULL if it looks at its priority and the priority is
less than or equal to 0? For example, currently the hierarch
component
returns NULL when its priority is equal or less than 0. This means
that
as a user when I set the priority to 0 I am indicating that I do not
want the hierarch component selected at all.
Or, is the priority only used to specify relative behavior. So, it is
not to be used to completely deselect a component. To deselect, you
would need to use the ^component format.
That is where I am confused.
Rolf
Josh Hursey wrote:
Yeah (Sorry I didn't reply earlier).
Each component is asked for at least two items of information:
priority (int), and module (struct *).
The priority can range from [INT_MIN | INT_MAX] with the highest
priority selected, even if that priority is negative.
If the component does not want to be selected then it should return
NULL for the module value. This indicates to the selection logic that
no matter what the priority is set to the component should not be a
candidate for selection.
So a component is selectable if it returns a non-NULL value for the
module struct, and is not selectable if it returns NULL. The priority
only indicates relative rank between all available components.
Does that make sense? I should probably add this comment to the
mca_base_select function to preserve it. I'll make a bug for it so it
doesn't get lost.
-- Josh
On May 23, 2008, at 7:14 AM, Jeff Squyres wrote:
We may not have this uniform throughout the code base -- this is one
of the things we wanted to talk about in the Bay area meeting. I
believe that the allowable range for priorities should be [0, 100],
and that if you don't want to be selected, you should return NULL
(or
use some other mechanism to indicate that you didn't want to be
selected). That was the original intent of the MCA selection
mechanisms, at least.
Josh -- is this consistent with what you found when you
consolidated a
lot of this stuff?
On May 22, 2008, at 11:30 AM, Rolf vandeVaart wrote:
I know there was some recent discussion about priority of
components,
but I wanted to double check. I am trying to understand what
priority =
0 means.
My assumption is the following:
priority >= 0 means the component is selectable
priority < 0 means the component is not selectable
I ask this because in some of the collective code it looks like a
priority = 0 means not selectable. Not a big deal, but I am
trying to
fix a memory leak and I need to get this piece right. And I assume
that
priority < 0 will give one the same behavior as ^component but the
code
paths within Open MPI would be different.
Rolf
_______________________________________________
devel mailing list
de...@open-mpi.org
http://www.open-mpi.org/mailman/listinfo.cgi/devel
--
Jeff Squyres
Cisco Systems
_______________________________________________
devel mailing list
de...@open-mpi.org
http://www.open-mpi.org/mailman/listinfo.cgi/devel
_______________________________________________
devel mailing list
de...@open-mpi.org
http://www.open-mpi.org/mailman/listinfo.cgi/devel
--
=========================
rolf.vandeva...@sun.com
781-442-3043
=========================
_______________________________________________
devel mailing list
de...@open-mpi.org
http://www.open-mpi.org/mailman/listinfo.cgi/devel
--
Jeff Squyres
Cisco Systems
