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SST V15.0.0 Release Notes

SST V15.0.0 Release Notes
Fixed issues and significant code changes:

General

Checkpoint/restart support has been expanded and the APIs are now stable. Major changes from the 14.x series include support for checkpointing all standard library containers as well as pointers to containers, changes to the checkpoint output directories, and support for checkpointing StandardMem and SimpleNetwork interfaces.
- See the guide here.
The following element libraries have partial checkpoint support. See individual release notes for details.
- memHierarchy
- simpleElementExample
Balar (GPGPUsim) is reintroduced and is now integrated with the Vanadis RISC-V CPU model. The prior integration with Ariel via Pin2 is removed.
The new golem element library provides an accelerator modeling array-based in-situ computing. It can optionally use the CrossSim simulator.

Deprecation and Removal Notices

The ser & and ser | operators are deprecated. Use SST_SER instead.
Use of shared TimeConverters (via pointers returned from Core API functions) is deprecated. Core APIs that accepted a TimeConverter* have been updated to accept a TimeConverter instead. In SST 16.0, Core APIs that return TimeConverter pointers will be changed to return a TimeConverter instance instead. To prepare for this switch, change code to construct a local TimeConverter instance from a returned TimeConverter pointer as shown.
```
      // Old code
      TimeConverter* tc = registerClock(...);
         
      // New code
      TimeConverter tc = registerClock(...);
```
In SST input files, GlobalParams have been renamed to SharedParams to reflect the fact that they can be shared among elements but are not “global” as there can be multiple groups of SharedParams that are not shared across all elements.
Reminder: The Event::Handler and Clock::Handler handler types were deprecated in SST 14.0. Use Event::Handler2 and Clock::Handler2 instead.
- The Handler signatures will be switched to match Handler2 in SST 16.0.
- The name Handler2 will be deprecated at SST 16.0 and removed in SST 17.0.
- Update all elements to use the new signatures before or at SST 16.0. Switching before SST 16.0 will require changing (Handler<class> -> Handler2<class,&class::callback_function>) prior to SST 16.0 and then to (Handler<class, &class::callback_function>) after 16.0. Waiting until SST 16.0 to switch will cause your code to break in SST 16.0 until you change the definition of (Handler<class> -> Handler<class, &class::callback_function>).
SST-Macro is a maintenance-only development effort. Due to increasing divergence between the SST-Core and SST-Macro, we will no longer be ensuring that the SST-Core and SST-Macro devel branches stay in sync. However, we will continue to ensure that the master branches and releases of SST-Macro work with SST-Core. Where possible, we recommend using the mercury element instead of SST-Macro. If mercury is missing key functionality present in SST-Macro that is not found elsewhere in SST-Elements, please let us know.

Known Issues

The OpenMPI 4.1.1 available through Rocky Linux and other OS distributions masks SST’s error return codes which causes some SST tests to fail. A workaround is to use OpenMPI 4.1.6.

SST-Core

New Features

Added ability to alias element names using SST_ELI_REGISTER_ALIAS
Added a CacheFlush instruction to the StandardMem interface
A new element type, PortModule, can attach to a port on a component and inspect, modify, or delete events sent or received through that port.
Added support for statistics in JSON input files
A new FileSystem utility class was added - see note below under “bug fixes”
Added a RealTimeAction for InteractiveConsole, allowing users to configure SST to drop into a interactive console on when SST receives a signal.
Expanded serialization support to include:
- All standard containers
- Pointers to standard containers
- SST::Interfaces::StandardMem and SST::Interfaces::SimpleInterface
A new SST_SER macro replaces serialization using ser & and ser |. The macro accepts flags describing how an object should be serialized and/or mapped (e.g., SerOption::as_ptr, SerOption::nomap).
Added new SST options to control checkpoint directories and names.

Bug Fixes

Fixed issue where the –output-directory parameter had no effect on files generated by SST-Core. Statistics and checkpoints now use this directory. In addition, a FileSystem class was added that contains utility functions for managing files in the output directory.
Fixed a bug with two different parameter names used for the same thing in statistics: the parameter resetOnRead should be resetOnOutput.
Fixed bug where sst-info would not generate output if a specific element was searched
Fixed issue where UnitAlgebra::trim() could read past the end of a 0-length string
Fixed issue where SST options did not correctly parse times given in seconds but greater than 1 minute (e.g., 90s). Note that this fixes seconds only: times in minutes but greater than 1 hour will not parse correctly.
Fixed several memory leaks discovered using Valgrind

General updates, changes, and cleanup

The checkpoint API is now stable; future changes will include a deprecation period with backwards compatibility
Added an AttachPoint concept to consolidate ProfilePoints with the new PortModule type.
Numerous code cleanup, modernization, and style changes
SST-Core is now using clang-format v20 instead of v12
Memory optimization: updated Statistics classes so that statistics that are not enabled consume significantly less memory while enabled statistics consume slightly less memory
Memory optimization: The config graph is now deleted properly after simulation construction
Updates to work with Python 3.13
Added an include guard to sst_config.h. The file is not yet included in SST-Core headers so developers should continue to include the file in elements. However, it may now be included safely in headers.

SST-Elements

New libraries
- golem models array-based in-situ computing and can optionally integrate with CrossSim
- balar is reintroduced and integrated with the Vanadis RISC-V model
General updates
- Numerous code clean up and modernization updates
- Added an include guard to sst_element_config.h
ariel
- The old integration with balar is removed
- Added latency tracking statistics
- Changed build to install libarielapi.so as part of the sst-elements install
- Fixed issue with libarielapi and mpi-related files when building out of source
balar
- SST 15.0 re-releases balar as an integration with the Vanadis RISC-V model
- Added support for using balar as an mmio device in a Vanadis simulation
- Balar creates a custom CUDA runtime lib to run CUDA programs with Vanadis
- New example to compile CUDA source code into RISC-V + CUDA to run with Vanadis + Balar
- Added more CUDA runtime APIs to support rodinia-2.0 benchmark
- Added CUDA stream APIs to support the basic simpleStreams example from cuda-samples
  - Support for cudaMemcpyAsync and launch kernels in different streams
- Redesign of balar frontend handling and callback functions from GPGPU-Sim
  - Now there is a light-weight “stream manager” in balar to track kernel calls and memcpy pushed to GPGPU-Sim
  - Callbacks to balar in GPGPU-Sim now will be handled by a single function in balar
- Redesigned dmaEngine to support multiple concurrent DMA copies with overlapping memory range check
- Added more unit test tests under different testsuites based on test runtime.
ember
- Extended the OTF2 motif in Ember so that it can read the global string definitions from an OTF2 trace into memory.
memHierarchy
- Added CacheFlush instruction which flushes the entire cache. Simulations can also now be configured to flush caches at shutdown and write out the contents of memory.
- Added checkpoint support for the following elements: Bus, MemLink. MemNIC, standardInterface, MemController (without the backing store), and standardCPU
- Added ability to read memory contents during SST’s init() phase (write was already supported).
- Code cleanup and removal of unused parameters
- Standardized port names across all elements in memHierarchy
  - Ports leading towards a processing unit are named “highlink”. For components with multiple ports, the names are “highlink0”, “highlink1”, etc.
  - Ports leading towards memory are named “lowlink”. For components with multiple ports, the names are “lowlink0”, “lowlink1”, etc.
  - Components such as MemNIC with a single port that can go in either direction are simply named “port”
- Added support for Ramulator2 as a backend
- Removed support for DRAMSim2 and associated backends including NVDIMMSim, HybridSim, and HBMDramSim2. The backends still exist in the code in this release but will no longer be tested.
mercury
- Significant code clean up, modernization, and debug improvements
- Fixed issue with packetization
- Added TLS to support variable privatization
- Added delay modeling
- There is a known race that occurs occasionally when SST is running with multiple threads. This will be fixed in a future release.
merlin
- Fixed memory leak with insufficient send credits
- Fixed some typos in pymerlin
miranda
- Eliminate high-overhead dynamic_cast
simpleElementExample
- Fixed crash that occurred during checkpoint of example subcomponents
vanadis
- Refactored VanadisInstruction, VanadisBasicLSQ, and decoder classes to improve code reuse and readability as well as support future SIMT pipeline capabilities.
- Added support for getcpu, sched_yield, hw_probe, and get/setaffinity syscalls
- Added OpenMP testing and examples
- Added a RoCC interface
- Added support for balar integration

SST-Macro

As of this release, macro’s devel branch is no longer being kept in sync with sst-core’s devel branch. The master branches and releases will continue to be kept in sync. This means there may be times when the sst-macro and sst-core devel branches do not work together.
Updated for LLVM 18
Various updates to work with sst-core’s updated serialization capabilities.
There is a known issue compiling SST-Macro with Python 3.13+. This will be fixed in a future release.

Fixed issues and significant code changes:

SST-Core

16 Trac: #434 SST Checkpointing no Longer Works

394 Change raw pointers to unique_ptr for static variables in new ELI

808 –enable-perf-tracking –enable-profile crashes

998 OpenMPI 4.1.x does not build with Apple Xcode 15

1049 StdMem cache flush enhancement

1058 External SST::Statistics libraries do not have access to core simulation object

1066 Support for SST::Statistics handlers in JSON input files

1068 Add PortModules to core API

1069 Compilation warnings with default OpenMPI on Ubuntu 22.04

1096 Add support for real-time events and custom signal handlers

1099 Output to File Output Location Causes Segmentation Fault

1118 Flag –enable-perf-tracking causes build to fail

1162 Fixes uninitialized object segfault in debugger

1165 checkpoint-wall-clock not recognizing simple seconds-only format

1168 Header file cleanup for ELI and serialization headers.

1169 Add [[noreturn]] attribute to SST::Output::fatal()

1171 Fix spelling mistake in test framework method

1173 Added the ability to register an alias for an element

1175 Add [[noreturn]] attribute to Output::fatal, add SST_Exit() function

1176 Fix type annotations in sst_unittest_support.py

1179 Remove dead log calls and consolidate logic in PIN support functions

1180 Add CacheFlush instruction to StandardMem interface

1183 sst-info failing component search

1184 Python: update logic between discover_and_run_tests and startup_and_run

1185 Attach Points

1187 Python: add type annotations to testingframework/test_engine.py

1188 Added missing attachInterceptTool() call to SSTHandlerBase

1190 Update for Python 3.13: Add new tp_versions_used field

1191 test_engine_globals.py: add type annotations and update uninitialized variables

1194 test_engine_junit.py: add type annotations

1195 Fix bug in sst-info filtering

1197 sst_unittest.py: add type annotations to run_sst

1198 test_engine_support.py: add type annotations

1201 Added support for PortModules.

1202 Enforce Python type annotations in continuous integration

1203 Import Python Coverage

1208 Optimize statistics memory usage

1210 Handle zero-length string in UnitAlgebra::trim()

1211 Replace MethodDetect<…> with std::void_t<…>

1212 Simplify SST_ELI_COMPILED_VERSION

1213 Combine combineEliInfo() implementations

1216 output-directory option has no effect

1217 Change typedef declarations to modern using aliases

1218 Use C++17 nested namespaces; remove using namespace std

1219 Empty (void) parameter lists

1220 Use _t and _v traits instead of ::type and ::value

1222 Use Meyers singletons

1224 Remove compiler warnings; move all MPI stuff into sst_mpi.h

1225 Add ability to break to interactive console on SIGUSR1/2

1227 Fix missed override in statnull.h

1229 Use std::vector for varying sized buffers

1230 Use std::unique_ptr with modelGen

1231 Allow user to specify seconds-only wall time in either S or Ss format

1233 Use modern techniques to delete copy constructors and assignment operators

1236 Update clang-format to something more modern

1238 adding json stats support

1240 Python command ordering induces I/O error with simulated model outputs

1242 Add more patterns to .gitignore

1244 fix typos

1248 Clean up UNUSED() macro

1251 Reformat long TimeVortex string messages to be split across lines.

1252 Add = delete declarations for copy constructors and copy assignment operators which are not needed

1253 Add “explicit” to constructors with a single parameter which should not perform implicit conversions

1254 Add [[noreturn]] to non-virtual functions which do not return

1255 Use std::make_unique() for variable-length arrays instead of array[N] when N is not constant

1256 Add __attribute__((format(…))) to printf-style functions which take format strings

1257 Add virtual destructors to classes with virtual functions and no declared destructor

1259 Reformat sst-config print_usage() to use one call to fputs()

1260 Inline trivial default constructors and destructors

1261 Add override for virtual functions which are overriden

1262 sst-test-core not running serial jobs

1263 Fix Valgrind memory errors

1264 Output directory fix

1266 Interactive console realtime action

1267 Fix #1262 by specifying intended base class

1269 Add include guard to sst_config.h

1271 Generalize serialize to support more containers in a generalized way, and store mapping name in a stack stored in the serializer

1272 Fixes for HDF5 stat output and test

1275 Checkpointing a simulation that started from a checkpoint induces segmentation fault

1276 Added WatchPoints and enabled them in SimpleDebug

1278 Fix config output

1279 Add necessary header #includes

1280 Updates to checkpointing.

1281 Update GitHub Actions runners to Ubuntu 24.04

1282 Replace incorrect usage of std::is_fundamental with std::is_arithmetic

1283 Fix Checkpoint tests for larger partition counts.

1284 Migrate OSCommand into public API for sst-test

1285 Use .clear() and .reserve() when unpacking containers; handle maps with simple keys which can be converted to string

1286 adding shared stats writing from JSON; Fix for JSON portion of Issue #1240

1290 Add testing_check_is_nightly() function

1291 StandardMem Serialization

1293 Serialize arrays, making the code much simpler and more general

1296 Use in-place serialization of container elements

1298 Finalize serialization API for checkpointing.

1300 Deprecated Handler in favor of Handler2.

1301 Deprecate use of shared TimeConverter* objects

1302 Fix enum warnings and make SerOption tests uniform

1303 Merge pointer and non-pointer serialize_impl adapter implementations

1306 Change name of GlobalParams to SharedParams for clarity.

1307 Tc updates

1309 latest dev branch fails compilation on rocky93/clang17

1310 TimeConverter fix

1312 Update help for –checkpoint-prefix to reflect that checkpoint index now starts at 1 instead of 0

1313 Serialize array bug

1314 Bug fix for timeconverter/basecomponent API

1315 Massage casting to remove warnings on GCC 14

1316 Fix some warnings found in gcc 8.5-14.2

1319 add array serialization tests, fix bugs

1320 Changed help messages to reflect features that are no longer experimental

1321 Bump clang-format requirement from v12 to v20

1322 Update to clang-format v20

SST-Elements

15 Trac: #282 Tests/Verify the LLSC feature from MemHierarchy

1430 memHierarchy: Support for Cache Flush

2368 balar build problem, no libcudart_mod.so

2404 Balar does not compile as written

2405 Vanadis - Refactoring codebase to modularize instruction and LSQ definitions

2410 Mercury: fix packetization

2411 miranda: check request operation instead of using dynamic_cast

2417 FlushAll

2419 Mercury: major code cleanup and debugging improvements

2422 merlin/linkcontrol: fix memory leak on insufficient send credits

2425 Mercury: delay modeling and parameter passing

2427 Remove calls to deprecated Python test framework functions

2430 MemH: Cache flushes and standardize port naming

2432 memH: Clean up unused code and parameters in memHierarchy.Bus

2433 Mercury: parameter clean-up

2436 Add latency tracking to Ariel

2437 Cleanup the build a tiny bit

2438 CUDA Buildsystem Outdated

2441 unittest: replace assertEquals with assertEqual

2442 Added getcpu, sched_yield, setaffinity syscalls to Vanadis. Added OpenMP examples.

2443 memH: Add automatic cache flush at shutdown

2446 Merlin: a typo in topology/pymerlin-topo-mesh.py script

2447 Merlin: fix typo in pymerlin-topo-mesh script

2448 Add RoCC interface to Vanadis

2450 Ember: adds reading global string definitions from OTF2 traces

2454 Fix iterator type mismatches caused by the std::map comparison functor being left out

2455 Add new element, golem

2458 Install libarielapi.so as part of installing sst-elements

2460 In Merlin, use SST:RNG::MersenneRNG instead of bare MersenneRNG

2461 Significantly reduce compiler warnings in SST Elements

2463 checkpoint crash for subcomponent

2464 Subcomponent fix for checkpointing

2467 CUDA cleanup on ariel aisle

2468 Fix warnings / errors with mremap

2470 Mercury: support for multiple tasks per node

2471 fix_balar_build: add check for CUDA and fix compilation warnings

2472 Add include guard to sst_element_config.h

2475 remove unnecessary UNUSED() macros in declarations (not definitions)

2476 Add TLS to Mercury

2477 Fix: set/get Affinity

2478 Add #include to a bunch of headers

2482 Ramulator 2 integration and namespacing of memH Debug macros

2483 Static analysis detected memory allocation issues

2484 Fix use_after_move

2485 Golem fix: check for crosssim library

2486 Initialize sumi return values

2487 Add override to overriden functions to remove Clang warnings

2488 fix misc warnings

2489 memH: Add ability to read memory during init()

2490 Temporarily disable checkpoint test in SimpleElementExample

2491 distclean Inadvertently Removes Files From In-Source Builds

2492 Fix for api and mpi file deletion when building in-source

2495 Add dummy hw_probe syscall for rv64

2496 Change Hg serialization to use serialize_impl instead of serialize.

2497 sst-elements autoconf script has trailing whitespace

2502 Disable long running tests for non-Nightly tests

2503 Update ser& to SER_SST for all elements except memH

2504 Move from using TimeConverter* to TimeConverter

2505 Moved Handler to Handler2.

2506 Update cramSim tests

2508 Add basic serialization to memh

2509 MemH: Checkpoint support for some memH components

2512 Replace Variable Length Arrays with arrays allocated with std::make_unique

2513 Deprecation fixes and compile warnings

2514 Mercury: skip the test_testme() method

SST-Macro

724 Update to llvm 18

726 Updates to serialization to support new serialization APIs in sst-core