Repository files navigation

• New YASK users may want to start withtheYASK tutorial.
• Users with existing YASK-based code may want to jump tothebackward-compatibility notices.
• All YASK users will also be interested intheAPI documentation.

YASK is a framework to rapidly create high-performance stencil codeincluding optimizations and features such as

• Support for boundary layers and staggered-grid stencils.
• Vector-folding to increase data reuse via non-traditional data layout.
• Multi-level OpenMP parallelism to exploit multiple CPU cores and threads.
• OpenMP offloading to GPUs.
• MPI scaling to multiple sockets and nodes with overlapped communication and compute.
• Spatial tiling with automatically-tuned block sizes.
• Temporal tiling in multiple dimensions to further increase cache locality.
• APIs for C++ and Python.

YASK contains a domain-specific compiler to convert stencil-equation specifications tooptimized code for Intel(R) Xeon(R) processors, Intel(R) Xeon Phi(TM) processors,and Intel(R) graphics processors.

• 64-bit Linux.
• Intel(R) Xeon(R) processors supporting the AVX, AVX2, or CORE_AVX512 instruction sets.
• Intel(R) Xeon Phi(TM) x200-family processors supporting the MIC_AVX512 instruction set (KNL).
• Intel(R) graphics processors supporting UHD graphics, e.g., Intel(R) Data Center GPU Max Series products.

• Intel(R)oneAPIHPC Toolkit for Linux (toolkit 2024.1 or later recommended); this will installthe Intel(R) oneAPI DPC++/C++ Compiler and the Intel(R) MPI Library.See compiler notes below under version 4.00.00 changes.
• Gnu C++ compiler, g++ (8.5.0 or later recommended).(Even when using Intel compilers, a g++ installation is required.)
• Linux librarieslibrt andlibnuma.
• Grep.
• Perl (v5 or later).
• Awk.
• Gnu make.
• Bash shell.
• Numactl utility if running on more than one CPU socket.
• Optional utilities and their purposes:
  • Theindent orgindent utility, used automatically during the build processto make the generated code easier for humans to read.You'll get a warning when runningmake if one of these doesn't exist.Everything will still work, but the generated code will be difficult to read.Reading the generated code is only necessary for debug, performance analysis, etc.
  • SWIG (4.0.0 or later):http://www.swig.org, for creating the Python interface.
  • Python 3 (3.6.1 or later):https://www.python.org/downloads, for creating and using the Python interface.Included with Intel(R) oneAPI HPC Toolkit.
  • Pythonnumpy package for running Python interface tests.Included with Intel(R) oneAPI HPC Toolkit.
  • Doxygen (1.9.0 or later):https://www.doxygen.nl, for creating updated API documentation.If you're not changing the API documentation, you can view the existing documentationat the link at the top of this page.
  • Graphviz (2.30.1 or later):http://www.graphviz.org, for rendering stencil diagrams.
  • Intel(R) Software Development Emulator:https://software.intel.com/en-us/articles/intel-software-development-emulator,for functional testing if you don't have native support for the targeted instruction set.

• Version 4.05.03 has a few notices:
  • The default stencil name "iso3dfd" is removed; this meansyou must always set the stencil name when building a kernel -- there is no default.If you get an error about the "unspecified" stencil, this means you didn't set thestencil name.
  • Some of the API-related Makefile target names were changed for consistency.
• Version 4.05.00 removes the "out-of-band" genetic-algorithm tuning scriptdue to lack of resources for maintenance and testing.
• Version 4.04.00 deprecates the existingvoid* {set,get}_elements_in_slice()APIs and provides saferfloat* anddouble* versions.
• Version 4.03.00 is a significant release with the following notices:
  • Each non-scratch stencil equation is now checked to ensureoffsets of +/-1 from the step-dimension on the LHS, e.g.,A(t+1, x, y) EQUALS B(t, x, y+1).(-1 is used for less-common reverse-time stencils.)
  • Theyk_solution::get_var() API now throws an exception if thenamed var does not exist. (Used to returnstd::nullptr.)
  • Vector "clustering" (unrolling by the YASK compiler) is nolonger supported.
  • Read-ahead in the inner-loop is no longer supported.
  • APIs for getting OpenMP thread counts were added.
  • Equation "bundles" are now called solution "parts".
• Version 4.01.00 added several new APIs.The following changes were made to to the YASK compiler:removed the-eq_bundles option, andan exception is now thrown fromoutput_solution() if theformat string is unrecognized.
• Version 4.00.00 was a major release with a number of notices:
  • Support has been added for GPU offloading via the OpenMP device model.Build any YASK stencil kernel withmake offload=1 .... This will createa kernel library and executable with an "arch" field containing"offload" and the OpenMP device target name.Usemake offload=1 offload_arch=<target> to change the OpenMP target;the default isspir64, for GPUs with Intel(R) Architecture (e.g., Gen12).Usemake offload_usm=1 to use the OpenMP Unified Shared Memory model.
  • The default compiler is now the Intel(R) oneAPI C++ compiler, icpx.If you want to use a different compiler, usemake YK_CXX=<compiler> ...for the kernel, and/ormake YC_CXX=<compiler> ... for the YASK compiler,ormake CXX=<compiler> for both. A C++ compiler that supports C++17is now required.
  • The loop hierarchy has been extended and renamed with (hopefully)more memorable names:version 3's regions, blocks, mini-blocks, and sub-blocksare now mega-blocks, blocks, micro-blocks, and nano-blocks,respectively.Pico-blocks have been added inside nano-blocks.When offloading, the nano-blocks and pico-blocks are executed on the device.The looping behaviors, including any temporal tiling, of mega-blocks,blocks, and micro-blocks are handled by the CPU.Theget_region_size() andset_region_size() APIs have been removed.The-r and-sb options, e.g.,-rx and-sbx, have also been removed.
  • Regarding CPU threads, "region threads" are now referred to as "outer threads",and "block threads" are now referred to as "inner threads".The option-block_threads is deprecated.The option-thread_divisor has been removed.See the-help documentation for new options-outer_threads and-inner_threads.The-max_threads option remains.
  • Only one thread per core is now used by default on most CPU models.This is done inyask.sh by passing-outer_threads <N> to the executable,where<N> is the number of cores on the node divided by thenumber of MPI ranks.Consequently, the default number of inner threads is now one (1)to use one core per block.This change was made based on observedperformance on newer Intel(R) Xeon(R) Processors. Previous versionsused two threads per block by default and used both hyper-threads ifthey were enabled. To configure two hyper-threads to work cooperativelyon each block, use the option-inner_threads 2.These changes do notapply to Intel(R) Xeon Phi(TM) x200-family processors (KNL), whichcontinue to use all 4 hyper-threads per core and 8 inner threadsby default (because 2 cores share an L2 cache).
  • Intel(R) Xeon Phi(TM) x100-family processors (KNC) are no longer supported.(Intel(R) Xeon Phi(TM) x200-family processors (KNL) are still supported.)
  • Python v2 is no longer supported.
  • New vector APIs were added toyk_solution andyk_var to allow gettingor setting multiple dimensions in one API call.
  • new_relative_var_point() API is deprecated.
  • APIs that were previously deprecated in theyk_var class have been removed.
  • Explicit support for persistent-memory devices has been removed.(Persistent-memory accessible via separate NUMA nodes or other standardLinux mechanisms is supported as with any other special memory types,e.g., high-bandwidth memory.)

• Version 3.05.00 changed the default setting of-use_shm totrue.Use-no-use_shm to disable shared-memory inter-rank communication.
• Version 3.04.00 changed the terms "pack" and "pass" to "stage", which may affectuser-written result parsers. Optionauto_tune_each_pass changed toauto_tune_each_stage.
• Version 3.01.00 moved the-trace and-msg_rank options from the kernellibrary to the kernel utility, so those options may no longer be set viayk_solution::apply_command_line_options(). APIs to set the correspondingoptions are now inyk_env. This allows configuring the debug outputbefore ayk_solution is created.
• Version 3.00.00 was a major release with a number of notices:
  • The old (v1 and v2) internal DSL that used undocumented types such asSolutionBase andGridValue and undocumented macros such asMAKE_GRID was replaced with an expanded version of the documented YASKcompiler API. Canonical v2 DSL code should still work using theSoln.hpp backward-compatibility header file. To convert v2 DSL codeto v3 format, use the./utils/bin/convert_v2_stencil.pl utility.Conversion is recommended.
  • For both the compiler and kernel APIs, all uses of the term "grid" werechanged to "var". (Historically, early versions of YASK allowed onlyvariables whose elements were points on the domain grid, so the termswere essentially interchangeable. Later, variables became more flexible.They could be defined with a subset of the domain dimensions, includenon-domain or "miscellaneous" indices, or even be simple scalar values,so the term "grid" to describe any variable became inaccurate. Thischange addresses that contradiction.) Again, backward-compatibilityfeatures in the API should maintain functionality of v2 DSL and kernelcode.
  • The default strings used in the kernel library and filenames to identifythe targeted architecture were changed from Intel CPU codenames to[approximate] instruction-set architecture (ISA) names "avx512", "avx2","avx", "knl", "knc", or "intel64". The YASK targets used in the YASKcompiler were updated to be consistent with this list.
  • The "mid" (roughly, median) performance results are now the firstones printed by theutils/bin/yask_log_to_csv.pl script.
  • In general, any old DSL and kernel code or user-written output-parsingscripts that use any undocumented files, data, or types may have to beupdated.

• Version 2.22.00 changed the heuristic to determine vector-folding sizes when somesizes are specified. This did not affect the default folding sizes.
• Version 2.21.02 simplified the example 3-D stencils (3axis,3plane, etc.)to calculate simple averages like those in the MiniGhost benchmark.This reduced the number of floating-point operations but not the number of points readfor each stencil.
• Version 2.20.00 added checking of the step-dimension index value in theyk_grid::get_element() and similar APIs.Previously, invalid values silently "wrapped" around to valid values.Now, by default, the step index must be valid when reading, and the valid stepindices are updated when writing.The old behavior of silent index wrapping may be restored viaset_step_wrap(true).The default for allstrict_indices API parameters is nowtrue to catch moreprogramming errors andincrease consistency of behavior between "set" and "get" APIs.Also, the advancedshare_storage() APIs have been replaced withfuse_grids().
• Version 2.19.01 turned off multi-pass tuning by default. Enable with-auto_tune_each_pass.
• Version 2.18.03 allowed the default radius to be stencil-specific and changed the namesof example stencil "9axis" to "3axis_with_diags".
• Version 2.18.00 added the ability to specify the global-domain size, and it will calculatethe local-domain sizes from it.There is no longer a default local-domain size.Output changed terms "overall-problem" to "global-domain" and "rank-domain" to "local-domain".
• Version 2.17.00 determined the host architecture inmake andbin/yask.sh andnumber of MPI ranks inbin/yask.sh.This changed the old behavior ofmake defaulting tosnb architecture andbin/yask.sh requiring-arch and-ranks.Those options are still available to override the host-based default.
• Version 2.16.03 moved the position of the log-file name to the last column in the CSVoutput ofutils/bin/yask_log_to_csv.pl.
• Version 2.15.04 required a call toyc_grid::set_dynamic_step_alloc(true) to allow changing theallocation in the step (time) dimension at run-time for grid variables created at YASK compile-time.
• Version 2.15.02 required all "misc" indices to be yask-compiler-time constants.
• Version 2.14.05 changed the meaning of temporal sizes so that 0 means never do temporalblocking and 1 allows blocking within a single time-step for multi-pack solutions.The default setting is 0, which keeps the old behavior.
• Version 2.13.06 changed the default behavior of the performance-test utility (yask.sh)to run trials for a given amount of time instead of a given number of steps.As of version 2.13.08, use the-trial_time option to specify the number of seconds to run.To force a specific number of trials as in previous versions, use the-trial_steps option.
• Version 2.13.02 required some changes in perf statistics due to step (temporal) conditions.Both text output andyk_stats APIs affected.
• Version 2.12.00 removed the long-deprecated== operator for asserting equality betweena grid point and an equation. UseEQUALS instead.
• Version 2.11.01 changed the plain-text format of some of the performance data in thetest-utility output.Specifically, some leading spaces were added, SI multipliers for values < 1 were added,and the phrase "time in" no longer appears before each time breakdown.This may affect some user programs that parse the output to collect stats.
• Version 2.10.00 changed the location of temporary files created during the build process.This will not affect most users, although you may need to manually remove oldsrc/compiler/genandsrc/kernel/gen directories.
• Version 2.09.00 changed the location of stencils in the internal DSL from.hpp to.cpp files.See the notes inhttps://github.com/intel/yask/releases/tag/v2.09.00 if you have any newor modified code insrc/stencils.