From 2b51a2597d8abc884cc2529f4eb91bc94cca6d1b Mon Sep 17 00:00:00 2001 From: Brian Barrett Date: Tue, 19 Dec 2017 09:21:48 -0800 Subject: [PATCH] doc: Add README note about ARM/POWER hangs As documented in #4563 and #3697, there is an issue on ARM and POWER platforms when the atomic fifo assembly isn't inlined, which manifests as a hang. Document the issue and the work-around until a proper fix is committed. Signed-off-by: Brian Barrett --- README | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/README b/README index 37805680a1d..153d423ec80 100644 --- a/README +++ b/README @@ -140,6 +140,14 @@ General notes using the clang-4.0 system compiler. A workaround is to build Open MPI using the GNU compiler. +Platform Notes +-------------- + +- ARM and POWER users may experience intermittent hangs when Open MPI + is compiled with low optimization settings, due to an issue with our + atomic list implementation. We recommend compiling with -O3 + optimization, both for performance reasons and to avoid this hang. + Compiler Notes --------------