[mpich2-dev] [PATCH 1/1] Issue 4120: Fix attr alignment check from MPI_Aint to long alignment
Rajeev Thakur
thakur at mcs.anl.gov
Mon Mar 24 21:48:54 CDT 2008
64-bit Windows uses the LLP64 model where sizeof(long) is 4 whereas sizeof
pointer is 8.
Rajeev
_____
From: owner-mpich2-dev at mcs.anl.gov [mailto:owner-mpich2-dev at mcs.anl.gov] On
Behalf Of Jeff Parker
Sent: Monday, March 24, 2008 4:13 PM
To: mpich2-dev at mcs.anl.gov
Subject: Re: [mpich2-dev] [PATCH 1/1] Issue 4120: Fix attr alignment check
from MPI_Aint to long alignment
On 03/23/2008 04:26 PM, William Gropp wrote:
"This one is system-specific - some systems will require the MPI_Aint
alignment. This should probably be abstracted out and set based on the
requirements of the system."
Are you saying that on some systems, "long" is not the size of a pointer,
whereas "MPI_Aint" is? Are there really such systems that we need to be
concerned about? Standard C specifies that long and pointers are the same
size.
Assuming it needs to be configurable, I propose adding another configure.in
variable that is the numeric datatype of an attribute value. MPI_Aint is
supposed to be that datatype, but since MPI_Aint is also used for offsets,
extents, etc. requiring that it be 8 bytes, we must define something else.
MPI_Aint must be the datatype of an extent as spec'd for
MPI_Type_get_extent().
Jeff Parker
IBM Blue Gene Messaging
William Gropp <gropp at mcs.anl.gov>
Sent by: owner-mpich2-dev at mcs.anl.gov
03/23/2008 04:26 PM
Please respond to
mpich2-dev at mcs.anl.gov
To
mpich2-dev at mcs.anl.gov
cc
Jeff Parker/Rochester/IBM at IBMUS
Subject
Re: [mpich2-dev] [PATCH 1/1] Issue 4120: Fix attr alignment check from
MPI_Aint to long alignment
This one is system-specific - some systems will require the MPI_Aint
alignment. This should probably be abstracted out and set based on the
requirements of the system.
Bill
On Mar 21, 2008, at 10:14 AM, Jeff Parker wrote:
In the mpi/attr code, there were checks to ensure the attribute was aligned
on a void*
boundary. This check anded the pointer with sizeof(MPI_Aint)-1. In the
case of an
MPI_Aint being 8 bytes, this was forcing the attribute to be on an 8-byte
boundary, when
in fact a 4-byte boundary would do. Changed the and operation to use
sizeof(long)-1 instead.
Signed-off-by: Jeff Parker < <mailto:jjparker at us.ibm.com>
jjparker at us.ibm.com>
---
lib/mpi/mpich2/src/mpi/attr/attr_get.c | 7 +++++--
lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c | 7 +++++--
lib/mpi/mpich2/src/mpi/attr/type_get_attr.c | 7 +++++--
lib/mpi/mpich2/src/mpi/attr/win_get_attr.c | 9 ++++++---
4 files changed, 21 insertions(+), 9 deletions(-)
diff --git a/lib/mpi/mpich2/src/mpi/attr/attr_get.c
b/lib/mpi/mpich2/src/mpi/attr/attr_get.c
index 095c979..cc39822 100644
--- a/lib/mpi/mpich2/src/mpi/attr/attr_get.c
+++ b/lib/mpi/mpich2/src/mpi/attr/attr_get.c
@@ -93,8 +93,11 @@ int MPI_Attr_get(MPI_Comm comm, int keyval, void
*attr_value, int *flag)
int when the address of a pointer (or an address-sized int)
should have been used. We can test for this specific
case. Note that this code assumes sizeof(MPI_Aint) is
- a power of 2. */
- if (MPI_VOID_PTR_CAST_TO_MPI_AINT attr_value & (sizeof(MPI_Aint)-1)) {
+ a power of 2. Note that this formerly used MPI_Aint for the
+ address sized int, but since this is configurable and could
+ be larger than a pointer, we use long for the check, since
+ long is expected to be the size of a pointer.*/
+ if (MPI_VOID_PTR_CAST_TO_MPI_AINT attr_value & (sizeof(long)-1)) {
MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
}
# endif
diff --git a/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c
b/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c
index ce5c836..b243968 100644
--- a/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c
+++ b/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c
@@ -85,8 +85,11 @@ int MPI_Comm_get_attr(MPI_Comm comm, int comm_keyval,
void *attribute_val, int *
int when the address of a pointer (or an address-sized int)
should have been used. We can test for this specific
case. Note that this code assumes sizeof(MPI_Aint) is
- a power of 2. */
- if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val &
(sizeof(MPI_Aint)-1)) {
+ a power of 2. Note that this formerly used MPI_Aint for the
+ address sized int, but since this is configurable and could
+ be larger than a pointer, we use long for the check, since
+ long is expected to be the size of a pointer. */
+ if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof(long)-1)) {
MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
}
# endif
diff --git a/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c
b/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c
index 7547bbb..7a41051 100644
--- a/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c
+++ b/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c
@@ -87,8 +87,11 @@ int MPI_Type_get_attr(MPI_Datatype type, int type_keyval,
void *attribute_val,
int when the address of a pointer (or an address-sized int)
should have been used. We can test for this specific
case. Note that this code assumes sizeof(MPI_Aint) is
- a power of 2. */
- if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val &
(sizeof(MPI_Aint)-1)) {
+ a power of 2. Note that this formerly used MPI_Aint for the
+ address sized int, but since this is configurable and could
+ be larger than a pointer, we use long for the check, since
+ long is expected to be the size of a pointer. */
+ if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof(long)-1)) {
MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
}
# endif
diff --git a/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c
b/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c
index 5fbef66..921f018 100644
--- a/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c
+++ b/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c
@@ -82,9 +82,12 @@ int MPI_Win_get_attr(MPI_Win win, int win_keyval, void
*attribute_val,
/* A common user error is to pass the address of a 4-byte
int when the address of a pointer (or an address-sized int)
should have been used. We can test for this specific
- case. Note that this code assumes sizeof(MPI_Aint) is
- a power of 2. */
- if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val &
(sizeof(MPI_Aint)-1)) {
+ case. Note that this code assumes sizeof(long) is
+ a power of 2. Note that this formerly used MPI_Aint for the
+ address sized int, but since this is configurable and could
+ be larger than a pointer, we use long for the check, since
+ long is expected to be the size of a pointer. */
+ if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof(long)-1)) {
MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
}
# endif
--
1.5.3.7
William Gropp
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign
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