Hubert - The issue with MPI_Get_address() in your usage model is one of heterogeneity. If process A is 32 bit and trying to create an address to talk to process B (which is 64 bit), there's now a difference (this, of course, assumes that MPI_Aint is an int64_t in that MPI). Brian -- Brian W. Barrett Scalable System Software Group Sandia National Laboratories ________________________________________ From: [email protected] [[email protected]] on behalf of Hubert Ritzdorf [[email protected]] Sent: Thursday, March 14, 2013 10:56 AM To: MPI 3.0 Remote Memory Access working group Subject: [EXTERNAL] Re: [Mpi3-rma] Ticket for WG discussion Hi Jim, this sounds to me that addr2 = MPI_Aint_index (base, disp) is equivalent to MPI_Get_Address ((char *) base + disp, &addr2) Is this correct or where is the difference ? Or is "base" also a displacement relative to MPI_BOTTOM (in which case it might be signed in Fortran) and addr2 = MPI_Aint_index (base, disp) is equivalent to MPI_Get_address ((char *) MPI_BOTTOM + base + disp, &addr2) Hubert ________________________________________ From: [email protected] [[email protected]] on behalf of Jim Dinan [[email protected]] Sent: Thursday, March 14, 2013 4:05 PM To: [email protected] Subject: Re: [Mpi3-rma] Ticket for WG discussion A little clearer: The value returned is the address, relative to MPI_BOTTOM, resulting from the sum of base and disp. ~Jim. On 3/14/13 9:42 AM, Jim Dinan wrote:
Hi Hubert,
My apologies, the ticket is light on details. The proposed function is:
MPI_Aint MPI_Aint_index(MPI_Aint base, MPI_Aint disp);
This function interprets the base argument as an address relative to MPI_BOTTOM and the disp argument as a signed integer displacement. The value returned is the sum of these two values.
~Jim.
On 3/13/13 7:12 AM, Hubert Ritzdorf wrote:
Hi Jim,
Sorry, I have some problems with the interpretation of function MPI_Aint_index().
(*) What does MPI_Aint_index() return ? A target displacement which can be used in RMA functions such as MPI Put/Get or does it return an address such as MPI_Get_address () ?
(*) What is argument "base" ? An address returned by MPI_Get_address() of any address or a window base returned by MPI_Win_get_attr(win, MPI_WIN_BASE, &base, &flag) ? May "base" (as MPI_Aint) be transferred from a different process ?
Hubert ________________________________________ From: [email protected] [[email protected]] on behalf of Jim Dinan [[email protected]] Sent: Tuesday, March 12, 2013 9:08 PM To: [email protected] Subject: Re: [Mpi3-rma] Ticket for WG discussion
Hubert,
We have added a solution #3 to the ticket based on discussion in the working group today. That's our current proposal. Could you take a look and see if that will be Fortran compatible?
Thanks, ~Jim.
On 3/12/13 2:28 PM, Hubert Ritzdorf wrote:
Hi,
concerning Ticket 349. (*) In Fortran, the displacement for dynamic windows may be signed since MPI_BOTTOM of Fortran is not (void *) NULL.. (*) Fortran doesn't have unsigned integers, thus you cannot use a Fortran version of MPI_Disp for arithmetics (such as disp++). (*) MPI Displacements in general may be signed. They might be relative to any address.
Therefore, I can't see that the Proposed Solution 2 solves the problem.
Hubert
________________________________________ From: [email protected] [[email protected]] on behalf of Jim Dinan [[email protected]] Sent: Tuesday, March 12, 2013 5:12 PM To: MPI 3.0 Remote Memory Access working group Subject: [Mpi3-rma] Ticket for WG discussion
Hi All,
I would like to propose the following two tickets for discussion in today's WG meeting:
https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/349 https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/344
#349 is a bugfix that definitely needs to be addressed. #344 is an "elegance of the interface" ticket where I would like to poll the WG to determine the level of support and determine if this should be pursued.
I unfortunately need to duck out at 4pm today, so if possible, I propose that we discuss these at the beginning of the meeting.
Thanks! ~Jim. _______________________________________________ mpi3-rma mailing list [email protected] http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma
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