From 3e7d4f1af9bddbcdc8727c07748b3774f534de90 Mon Sep 17 00:00:00 2001 From: Howard Pritchard Date: Tue, 5 Jul 2016 13:30:01 -0600 Subject: [PATCH] README: document some thread support limitations Signed-off-by: Howard Pritchard --- README | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/README b/README index 29f667cc91..590efd24f4 100644 --- a/README +++ b/README @@ -448,8 +448,8 @@ MPI Functionality and Features deprecated_example.c:4: warning: 'MPI_Type_struct' is deprecated (declared at /opt/openmpi/include/mpi.h:1522) shell$ -- MPI_THREAD_MULTIPLE is supported. Note that Open MPI must be - configured with --enable-mpi-thread-multiple to get this +- MPI_THREAD_MULTIPLE is supported with some exceptions. Note that Open MPI + must be configured with --enable-mpi-thread-multiple to get this level of thread safety support. The following BTLs support MPI_THREAD_MULTIPLE: @@ -463,6 +463,13 @@ MPI Functionality and Features - MXM - portals4 + Currently MPI File operations are not thread safe even if + MPI is initialized for MPI_THREAD_MULTIPLE support. + + The OpenIB BTL's RDMACM based connection setup mechanism is also + not thread safe. The default UDCM method should be used for applications + requiring MPI_THREAD_MULTIPLE support. + - MPI_REAL16 and MPI_COMPLEX32 are only supported on platforms where a portable C datatype can be found that matches the Fortran type REAL*16, both in size and bit representation.