+Important user-visible changes:
+ - Surf precision default value is now 1e-9, instead of 1e-5. This was changed as
+ several users had difficult to understand issues when using high bandwidth or
+ small latency events. The new value was already the default for SMPI and
+ should not cause too much performance hit. It can change some simulation
+ timings if simulation was skipping a lot of small events (which was actually
+ an issue of said simulation). The value can still be changed back using
+ --cfg=surf/precision:1e-5.
+ - On some network models (L07, CM02, LV08), an implicit loopback link is created
+ for local communication. Default bandwidth was 500MBps and latency was 15µs,
+ which was rather bad. Default values have been changed to 10GBps and 0 latency.
+ Options network/loopback-lat and network/loopback-bw have been added to adapt
+ these values if needed. Network and routing models already providing separate
+ loopbacks (clusters and such) are not impacted by this change.
+ - SMPI now adds 16 bytes of header to each message sent, in order to simulate
+ metadata that are added to each MPI message by MPI libraries (tag,
+ src/dest, and communicator information). This may change simulation times
+ for very small message sizes, but should be more realistic.
+
+S4U:
+ - the on_exit() of each actor is also executed when the simulation deadlocks.
+
+SMPI:
+ - Update proxy apps coverage of new ECP apps: 60+ apps now tested nightly on
+ https://framagit.org/simgrid/SMPI-proxy-apps
+ - MPI/IO: supports names starting with "./"
+ - Fortran: many MPI/IO bindings, support for MPI_UB/LB, C MPI_INT/FLOAT/DOUBLE
+ datatypes.
+ - smpicc/cxx/ff/f90 now will actually perform definition checks at link time. When
+ building shared libraries, this may cause issues, so environment variable
+ SMPI_NO_UNDEFINED_CHECK can be added to disable this.
+
+C binding:
+ - The return type of the sg_actor_on_exit() callbacks is now 'void'
+ (int value was previously ignored)
+
+General:
+ - Require a compiler with C++14 support.
+ - LTO is now enabled for Intel/clang compilers.
+ - LTO behavior on GCC can be parameterized using LTO_EXTRA_FLAG in cmake.
+ Setting it to "auto" will use all available cores, while setting it to n will
+ use n cores to speedup link step (usage: cmake -DLTO_EXTRA_FLAG=4).
+