clang is a C compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking. Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
clang++ C++ compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking. Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
flang is a Fortran compiler which encompasses parsing, optimization, code generation, assembly, and linking. Depending on which high-level mode setting is passed, Flang will stop before doing a full link.
clang is a C compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking. Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
clang++ C++ compiler which encompasses preprocessing, parsing, optimization, code generation, assembly, and linking. Depending on which high-level mode setting is passed, Clang will stop before doing a full link.
flang is a Fortran compiler which encompasses parsing, optimization, code generation, assembly, and linking. Depending on which high-level mode setting is passed, Flang will stop before doing a full link.
This macro indicates that the benchmark is being compiled on an AMD64-compatible system running the Linux operating system.
This macro specifies that the target system uses the LP64 data model; specifically, that integers are 32 bits, while longs and pointers are 64 bits.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This flag can be set for SPEC compilation for LINUX using default compiler.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This macro indicates that the benchmark is being compiled on an AMD64-compatible system running the Linux operating system.
This macro specifies that the target system uses the LP64 data model; specifically, that integers are 32 bits, while longs and pointers are 64 bits.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This flag can be set for SPEC compilation for LINUX using default compiler.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
This option is used to indicate that the host system's integers are 32-bits wide, and longs and pointers are 64-bits wide. Not all benchmarks recognize this macro, but the preferred practice for data model selection applies the flags to all benchmarks; this flag description is a placeholder for those benchmarks that do not recognize this macro.
Generates code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64, x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target platform specified is 64-bit, otherwise the default is 32-bit.
Forces the alignment of all blocks that have no fall-through predecessors (i.e. don't add nops that are executed). In log2 format (e.g 4 means align on 16B boundaries).
This option eliminates the array computations based on their usage. The computations on unused array elements and computations on zero valued array elements are eliminated with this optimization. -flto as whole program analysis is required to perform this optimization.
Possible values:
Suppress error when linking multiple symbols of the same name.
Like -O2, except that it enables optimizations that take longer to perform or that may generate larger code (in an attempt to make the program run faster).
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify -march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but which may not exist on earlier products. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
Use the given vector functions library.
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is ignored even if set by the system headers.
Enable handling of OpenMP directives and generate parallel code. The openmp library to be linked can be specified through -fopenmp=library option.
Generate output files in LLVM formats suitable for link time optimization. When used with -S this generates LLVM intermediate language assembly files, otherwise this generates LLVM bitcode format object files (which may be passed to the linker depending on the stage selection options).
Analyzes the whole program to determine if the structures in the code can be peeled, if dead or redundant fields can be deleted, and if the pointer or integer fields in the structure can be compressed. If feasible, this optimization transforms the code to enable these improvements. This transformation is likely to improve cache utilization and memory bandwidth. It is expected to improve the scalability of programs executed on multiple cores. This is effective only under flto as the whole program analysis is required to perform this optimization. You can choose different levels of aggressiveness with which this optimization can be applied to your application; with 1 being the least aggressive and 7 being the most aggressive level.
Possible values:
fstruct-layout=4 and fstruct-layout=5 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added feature of safe compression of 64-bit integer fields to 32-bit integer fields in structures. Going from fstruct-layout=4 to fstruct-layout=5 may result in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
fstruct-layout=6 and fstruct-layout=7 are derived from fstruct-layout=2 and fstructlayout=3 respectively, with the added feature of safe compression of 64 bit integer fields to 16 bit integer in structures. Going from fstruct-layout=6 to fstruct-layout=7 may result in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
Sets the limit at which loops will be unrolled. For example, if unroll threshold is set to 100 then only loops with 100 or fewer instructions will be unrolled.
Sets the compiler's inlining threshold level to the value passed as the argument. The inline threshold is used in the inliner heuristics to decide which functions should be inlined.
This option enables an optimization that transforms the data layout of a single dimensional array to provide better cache locality by analysing the access patterns.
Enables loop strip mining optimization. This optimization breaks a large loop into smaller segments or strips to improve temporal and spatial locality.
This option eliminates the array computations based on their usage. The computations on unused array elements and computations on zero valued array elements are eliminated with this optimization. -flto as whole program analysis is required to perform this optimization.
Possible values:
Definition of this macro indicates that compilation for parallel operation is enabled, and that any OpenMP directives or pragmas will be visible to the compiler. The behavior of this macro is overridden if -DSPEC_SUPPRESS_OPENMP also appears in the list of compilation flags.
This option enables a subset of scalar, vector and loop transformations including improved variants of loop invariant code motion, SLP and loop vectorizations, loop-fusion, loop-interchange, loop-unswitch, loop tiling and loop distribution.
Enable handling of OpenMP directives and generate parallel code. The openmp library to be linked can be specified through -fopenmp=library option.
Instructs the compiler to link with the OpenMP runtime libraries.
Instructs the compiler to link with AMD-supported optimized math library.
Instructs the compiler to link with flang Fortran runtime libraries.
amdalloc is a AMD's memory allocator based on jemalloc library and is available as a part of AOCC binary package.
Generates code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64, x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target platform specified is 64-bit, otherwise the default is 32-bit.
Forces the alignment of all blocks that have no fall-through predecessors (i.e. don't add nops that are executed). In log2 format (e.g 4 means align on 16B boundaries).
This option eliminates the array computations based on their usage. The computations on unused array elements and computations on zero valued array elements are eliminated with this optimization. -flto as whole program analysis is required to perform this optimization.
Possible values:
Like -O2, except that it enables optimizations that take longer to perform or that may generate larger code (in an attempt to make the program run faster).
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify -march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but which may not exist on earlier products. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
Use the given vector functions library.
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is ignored even if set by the system headers.
Enable handling of OpenMP directives and generate parallel code. The openmp library to be linked can be specified through -fopenmp=library option.
Generate output files in LLVM formats suitable for link time optimization. When used with -S this generates LLVM intermediate language assembly files, otherwise this generates LLVM bitcode format object files (which may be passed to the linker depending on the stage selection options).
Sets the limit at which loops will be unrolled. For example, if unroll threshold is set to 100 then only loops with 100 or fewer instructions will be unrolled.
Sets the compiler's inlining heuristics to an aggressive level by increasing the inline thresholds.
Sets the limit at which loops will be unswitched. For example, if unswitch threshold is set to 100 then only loops with 100 or fewer instructions will be unswtched.
This option eliminates the array computations based on their usage. The computations on unused array elements and computations on zero valued array elements are eliminated with this optimization. -flto as whole program analysis is required to perform this optimization.
Possible values:
Definition of this macro indicates that compilation for parallel operation is enabled, and that any OpenMP directives or pragmas will be visible to the compiler. The behavior of this macro is overridden if -DSPEC_SUPPRESS_OPENMP also appears in the list of compilation flags.
This option enables a subset of scalar, vector and loop transformations including improved variants of loop invariant code motion, SLP and loop vectorizations, loop-fusion, loop-interchange, loop-unswitch, loop tiling and loop distribution.
Enables dead virtual function elimination optimization. Requires -flto=full.
Set the default symbol visibility for all global declarations.
Enable handling of OpenMP directives and generate parallel code. The openmp library to be linked can be specified through -fopenmp=library option.
Instructs the compiler to link with the OpenMP runtime libraries.
Instructs the compiler to link with AMD-supported optimized math library.
Instructs the compiler to link with flang Fortran runtime libraries.
amdalloc-ext is a AMD's memory allocator based on jemalloc library and is available as a part of AOCC binary package.
Generates code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64, x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target platform specified is 64-bit, otherwise the default is 32-bit.
Forces the alignment of all blocks that have no fall-through predecessors (i.e. don't add nops that are executed). In log2 format (e.g 4 means align on 16B boundaries).
This option eliminates the array computations based on their usage. The computations on unused array elements and computations on zero valued array elements are eliminated with this optimization. -flto as whole program analysis is required to perform this optimization.
Possible values:
Enables inlining for recursive functions based on heuristics, with level 4 being most aggressive. Higher levels may lead to code bloat due to expansion of recursive functions at call sites.
Levels:
Enables loop strength reduction for nested loop structures. By default, the compiler performs loop strength reduction only for the innermost loop.
Enables splitting of long live ranges of loop induction variables which span loop boundaries. This helps reduce register pressure and can help avoid needless spills to memory and reloads from memory.
Like -O2, except that it enables optimizations that take longer to perform or that may generate larger code (in an attempt to make the program run faster).
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify -march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but which may not exist on earlier products. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
Use the given vector functions library.
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is ignored even if set by the system headers.
Enable handling of OpenMP directives and generate parallel code. The openmp library to be linked can be specified through -fopenmp=library option.
Generate output files in LLVM formats suitable for link time optimization. When used with -S this generates LLVM intermediate language assembly files, otherwise this generates LLVM bitcode format object files (which may be passed to the linker depending on the stage selection options).
Optimizes the cost model for strided accesses to memory.
Enables aggressive heuristics to get loop unrolling.
Sets the limit at which loops will be unrolled. For example, if unroll threshold is set to 100 then only loops with 100 or fewer instructions will be unrolled.
Enable handling of OpenMP directives and generate parallel code. The openmp library to be linked can be specified through -fopenmp=library option.
Instructs the compiler to link with the OpenMP runtime libraries.
Instructs the compiler to link with AMD-supported optimized math library.
Instructs the compiler to link with flang Fortran runtime libraries.
amdalloc is a AMD's memory allocator based on jemalloc library and is available as a part of AOCC binary package.
Generates code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64, x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target platform specified is 64-bit, otherwise the default is 32-bit.
Forces the alignment of all blocks that have no fall-through predecessors (i.e. don't add nops that are executed). In log2 format (e.g 4 means align on 16B boundaries).
This option eliminates the array computations based on their usage. The computations on unused array elements and computations on zero valued array elements are eliminated with this optimization. -flto as whole program analysis is required to perform this optimization.
Possible values:
Suppress error when linking multiple symbols of the same name.
Enables all the optimizations from -O3 along with other aggressive optimizations that may violate strict compliance with language standards. Refer to the AOCC options document for the language you're using for more detailed documentation of optimizations enabled under -Ofast.
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify -march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but which may not exist on earlier products. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
Use the given vector functions library.
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is ignored even if set by the system headers.
Enable handling of OpenMP directives and generate parallel code. The openmp library to be linked can be specified through -fopenmp=library option.
Generate output files in LLVM formats suitable for link time optimization. When used with -S this generates LLVM intermediate language assembly files, otherwise this generates LLVM bitcode format object files (which may be passed to the linker depending on the stage selection options).
Analyzes the whole program to determine if the structures in the code can be peeled, if dead or redundant fields can be deleted, and if the pointer or integer fields in the structure can be compressed. If feasible, this optimization transforms the code to enable these improvements. This transformation is likely to improve cache utilization and memory bandwidth. It is expected to improve the scalability of programs executed on multiple cores. This is effective only under flto as the whole program analysis is required to perform this optimization. You can choose different levels of aggressiveness with which this optimization can be applied to your application; with 1 being the least aggressive and 7 being the most aggressive level.
Possible values:
fstruct-layout=4 and fstruct-layout=5 are derived from fstruct-layout=2 and fstruct-layout=3 respectively with the added feature of safe compression of 64-bit integer fields to 32-bit integer fields in structures. Going from fstruct-layout=4 to fstruct-layout=5 may result in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
fstruct-layout=6 and fstruct-layout=7 are derived from fstruct-layout=2 and fstructlayout=3 respectively, with the added feature of safe compression of 64 bit integer fields to 16 bit integer in structures. Going from fstruct-layout=6 to fstruct-layout=7 may result in higher performance if the pointer values are such that the pointers can be compressed to 16-bits.
Sets the limit at which loops will be unrolled. For example, if unroll threshold is set to 100 then only loops with 100 or fewer instructions will be unrolled.
This option enables an optimization that transforms the data layout of a single dimensional array to provide better cache locality by analysing the access patterns.
Enables loop strip mining optimization. This optimization breaks a large loop into smaller segments or strips to improve temporal and spatial locality.
Sets the compiler's inlining threshold level to the value passed as the argument. The inline threshold is used in the inliner heuristics to decide which functions should be inlined.
This option eliminates the array computations based on their usage. The computations on unused array elements and computations on zero valued array elements are eliminated with this optimization. -flto as whole program analysis is required to perform this optimization.
Possible values:
Definition of this macro indicates that compilation for parallel operation is enabled, and that any OpenMP directives or pragmas will be visible to the compiler. The behavior of this macro is overridden if -DSPEC_SUPPRESS_OPENMP also appears in the list of compilation flags.
This option enables a subset of scalar, vector and loop transformations including improved variants of loop invariant code motion, SLP and loop vectorizations, loop-fusion, loop-interchange, loop-unswitch, loop tiling and loop distribution.
Enable handling of OpenMP directives and generate parallel code. The openmp library to be linked can be specified through -fopenmp=library option.
Instructs the compiler to link with the OpenMP runtime libraries.
Instructs the compiler to link with AMD-supported optimized math library.
amdalloc is a AMD's memory allocator based on jemalloc library and is available as a part of AOCC binary package.
Instructs the compiler to link with flang Fortran runtime libraries.
Generates code for a 64-bit environment. The 64-bit environment sets int to 32 bits and long and pointer to 64 bits and generates code for AMD's x86-64 architecture. The compiler generates AMD64, INTEL64, x86-64 64-bit ABI. The default on a 32-bit host is 32-bit ABI. The default on a 64-bit host is 64-bit ABI if the target platform specified is 64-bit, otherwise the default is 32-bit.
Forces the alignment of all blocks that have no fall-through predecessors (i.e. don't add nops that are executed). In log2 format (e.g 4 means align on 16B boundaries).
This option eliminates the array computations based on their usage. The computations on unused array elements and computations on zero valued array elements are eliminated with this optimization. -flto as whole program analysis is required to perform this optimization.
Possible values:
Block Reordering
Possible values:
Enables all the optimizations from -O3 along with other aggressive optimizations that may violate strict compliance with language standards. Refer to the AOCC options document for the language you're using for more detailed documentation of optimizations enabled under -Ofast.
Specify that Clang should generate code for a specific processor family member and later. For example, if you specify -march=znver1, the compiler is allowed to generate instructions that are valid on AMD Zen processors, but which may not exist on earlier products. -march=znver4 enables AVX 512 ISA for Genoa (znver4) processors.
Use the given vector functions library.
Enables a range of optimizations that provide faster, though sometimes less precise, mathematical operations that may not conform to the IEEE-754 specifications. When this option is specified, the __STDC_IEC_559__ macro is ignored even if set by the system headers.
Enable handling of OpenMP directives and generate parallel code. The openmp library to be linked can be specified through -fopenmp=library option.
Generate output files in LLVM formats suitable for link time optimization. When used with -S this generates LLVM intermediate language assembly files, otherwise this generates LLVM bitcode format object files (which may be passed to the linker depending on the stage selection options).
Sets the compiler's inlining heuristics to an aggressive level by increasing the inline thresholds.
Sets the limit at which loops will be unrolled. For example, if unroll threshold is set to 100 then only loops with 100 or fewer instructions will be unrolled.
This option eliminates the array computations based on their usage. The computations on unused array elements and computations on zero valued array elements are eliminated with this optimization. -flto as whole program analysis is required to perform this optimization.
Possible values:
Definition of this macro indicates that compilation for parallel operation is enabled, and that any OpenMP directives or pragmas will be visible to the compiler. The behavior of this macro is overridden if -DSPEC_SUPPRESS_OPENMP also appears in the list of compilation flags.
This option enables a subset of scalar, vector and loop transformations including improved variants of loop invariant code motion, SLP and loop vectorizations, loop-fusion, loop-interchange, loop-unswitch, loop tiling and loop distribution.
Block Reordering
Possible values:
Enables dead virtual function elimination optimization. Requires -flto=full.
Set the default symbol visibility for all global declarations.
Enable handling of OpenMP directives and generate parallel code. The openmp library to be linked can be specified through -fopenmp=library option.
Instructs the compiler to link with the OpenMP runtime libraries.
Instructs the compiler to link with AMD-supported optimized math library.
amdalloc-ext is a AMD's memory allocator based on jemalloc library and is available as a part of AOCC binary package.
Instructs the compiler to link with flang Fortran runtime libraries.
Do not warn about functions defined with a return type that defaults to "int" or which return something other than what they were declared to.
Do not warn about unused command line arguments.
Do not warn about unused command line arguments.
Do not warn about unused command line arguments.
Do not warn about functions defined with a return type that defaults to "int" or which return something other than what they were declared to.
Do not warn about unused command line arguments.
Do not warn about unused command line arguments.
Do not warn about unused command line arguments.
This section contains descriptions of flags that were included implicitly by other flags, but which do not have a permanent home at SPEC.
Somewhere between -O0 and -O2.
If multiple "O" options are used, with or without level numbers, the last such option is the one that is effective.
Using numactl
to bind processes and memory to cores
For multi-copy runs or single copy runs on systems with multiple sockets, it is advantageous to bind a process to a
particular core. Otherwise, the OS may arbitrarily move your process from one core to another. This can affect
performance. To help, SPEC allows the use of a "submit" command where users can specify a utility to use to bind
processes. We have found the utility 'numactl
' to be the best choice.
numactl
runs processes with a specific NUMA scheduling or memory placement policy. The policy is set for a
command and inherited by all of its children. The numactl
flag "--physcpubind
" specifies
which core(s) to bind the process. "-l
" instructs numactl
to keep a process's memory on the
local node while "-m
" specifies which node(s) to place a process's memory. For full details on using
numactl
, please refer to your Linux documentation, 'man numactl
'
Note that some older versions of numactl
incorrectly interpret application arguments as its own. For
example, with the command "numactl --physcpubind=0 -l a.out -m a
", numactl
will interpret
a.out
's "-m
" option as its own "-m
" option. To work around this problem, we put
the command to be run in a shell script and then run the shell script using numactl
. For example:
"echo 'a.out -m a' > run.sh ; numactl --physcpubind=0 bash run.sh
"
numactl --interleave=all runcpu
numactl --interleave=all runcpu
executes the SPEC CPU command runcpu
so that memory is consumed across NUMA nodes rather than consumed from a single node. This helps prevent local node out-of-memory conditions which can occur when runcpu
is executed without interleaving.
For full details on using numactl
, please refer to your Linux documentation, 'man numactl
'
Transparent Huge Pages (THP)
THP is an abstraction layer that automates most aspects of creating, managing, and using huge pages. It is designed to hide much of the complexity in using huge pages from system administrators and developers. Huge pages increase the memory page size from 4 kilobytes to 2 megabytes. This provides significant performance advantages on systems with highly contended resources and large memory workloads. If memory utilization is too high or memory is badly fragmented which prevents huge pages being allocated, the kernel will assign smaller 4k pages instead. Most recent Linux OS releases have THP enabled by default.
THP usage is controlled by the sysfs setting /sys/kernel/mm/transparent_hugepage/enabled
.
Possible values:
The SPEC CPU benchmark codes themselves never explicitly request huge pages, as the mechanism to do that is OS-specific and can change over time. Libraries such as amdalloc which are used by the benchmarks may explicitly request huge pages, and use of such libraries can make the "madvise" setting relevant and useful.
When no huge pages are immediately available and one is requested, how the system handles the request for THP creation is
controlled by the sysfs setting /sys/kernel/mm/transparent_hugepage/defrag
.
Possible values:
An application that "always" requests THP often can benefit from waiting for an allocation until those huge pages can be assembled.
For more information see the Linux transparent hugepage documentation.
ulimit -s <n>
Sets the stack size to n kbytes, or unlimited to allow the stack size to grow without limit.
ulimit -l <n>
Sets the maximum size of memory that may be locked into physical memory.
powersave -f
(on SuSE)
Makes the powersave daemon set the CPUs to the highest supported frequency.
/etc/init.d/cpuspeed stop
(on Red Hat)
Disables the cpu frequency scaling program in order to set the CPUs to the highest supported frequency.
LD_LIBRARY_PATH
An environment variable that indicates the location in the filesystem of bundled libraries to use when running the benchmark binaries.
LIBOMP_NUM_HIDDEN_HELPER_THREADS
target nowait
is supported via hidden helper task, which is a task not bound to any parallel region. A hidden helper team with a number of threads is created when the first hidden helper task is encountered.
The number of threads can be configured via the environment variable LIBOMP_NUM_HIDDEN_HELPER_THREADS
. The default is 8. If LIBOMP_NUM_HIDDEN_HELPER_THREADS
is 0, the hidden helper task is disabled and support falls back to a regular OpenMP task. The hidden helper task can also be disabled by setting the environment variable LIBOMP_USE_HIDDEN_HELPER_TASK=OFF
.
sysctl -w vm.dirty_ratio=8
Limits dirty cache to 8% of memory.
sysctl -w vm.swappiness=1
Limits swap usage to minimum necessary.
sysctl -w vm.zone_reclaim_mode=1
Frees local node memory first to avoid remote memory usage.
kernel/numa_balancing
This OS setting controls automatic NUMA balancing on memory mapping and process placement. NUMA balancing incurs overhead for no benefit on workloads that are already bound to NUMA nodes.
Possible settings:
For more information see the numa_balancing
entry in the
Linux sysctl documentation.
kernel/randomize_va_space
(ASLR)
This setting can be used to select the type of process address space randomization. Defaults differ based on whether the architecture supports ASLR, whether the kernel was built with the CONFIG_COMPAT_BRK option or not, or the kernel boot options used.
Possible settings:
norandmaps
" parameter.CONFIG_COMPAT_BRK
option is enabled at kernel build time.CONFIG_COMPAT_BRK
is
disabled.
Disabling ASLR can make process execution more deterministic and runtimes more consistent.
For more information see the randomize_va_space
entry in the
Linux sysctl documentation.
vm/drop_caches
The two commands are equivalent: echo 3> /proc/sys/vm/drop_caches and sysctl -w vm.drop_caches=3 Both must be run as root. The commands are used to free up the filesystem page cache, dentries, and inodes.
Possible settings:
MALLOC_CONF
The amdalloc library is a variant of jemalloc library. The amdalloc
library has tunable parameters, many of which may be changed at run-time via several mechanisms, one of which
is the MALLOC_CONF
environment variable. Other methods, as well as the order in which they're referenced,
are detailed in the jemalloc documentation's TUNING section.
The options that can be tuned at run-time are everything in the jemalloc documentation's
MALLCTL NAMESPACE section that begins with
"opt.
".
The options that may be encountered in SPEC CPU 2017 results are detailed here:
retain:true
- Causes unused virtual memory to
be retained for later reuse rather than discarding it. This is the default for 64-bit Linux.oversize_threshold:0
- The threshold in bytes
of which allocation requests are considered oversize. The default threshold is 8MiB.thp:never
- Attempts to never utilize huge pages
by using MADV_NOHUGEPAGE
on all mappings. This option has no effect except when THP is set to
"madvise".PGHPF_ZMEM
An environment variable used to initialize the allocated memory. Setting PGHPF_ZMEM to "Yes" has the effect of initializing all allocated memory to zero.
GOMP_CPU_AFFINITY
This environment variable is used to set the thread affinity for threads spawned by OpenMP.
OMP_DYNAMIC
This environment variable is defined as part of the OpenMP standard. Setting it to "false" prevents the OpenMP runtime from dynamically adjusting the number of threads to use for parallel execution.
For more information, see chapter 4 ("Environment Variables") in the OpenMP 4.5 Specification.
OMP_SCHEDULE
This environment variable is defined as part of the OpenMP standard. Setting it to "static" causes loop iterations to be assigned to threads in round-robin fashion in the order of the thread number.
For more information, see chapter 4 ("Environment Variables") in the OpenMP 4.5 Specification.
OMP_STACKSIZE
This environment variable is defined as part of the OpenMP standard and controls the size of the stack for threads created by OpenMP.
For more information, see chapter 4 ("Environment Variables") in the OpenMP 4.5 Specification.
OMP_THREAD_LIMIT
This environment variable is defined as part of the OpenMP standard and limits the maximum number of OpenMP threads that can be created.
For more information, see chapter 4 ("Environment Variables") in the OpenMP 4.5 Specification.
Model | Normal TDP | Minimum TDP | Maximum TDP |
---|---|---|---|
EPYC 9654 | 360 | 320 | 400 |
EPYC 9654P | 360 | 320 | 400 |
EPYC 9634 | 290 | 240 | 300 |
EPYC 9554 | 360 | 320 | 400 |
EPYC 9554P | 360 | 320 | 400 |
EPYC 9534 | 280 | 240 | 300 |
EPYC 9474F | 360 | 320 | 400 |
EPYC 9454 | 290 | 240 | 300 |
EPYC 9454P | 290 | 240 | 300 |
EPYC 9374F | 320 | 320 | 400 |
EPYC 9354 | 280 | 240 | 300 |
EPYC 9354P | 280 | 240 | 300 |
EPYC 9334 | 210 | 200 | 240 |
EPYC 9274F | 320 | 320 | 400 |
EPYC 9254 | 200 | 200 | 240 |
EPYC 9224 | 200 | 200 | 240 |
EPYC 9174F | 320 | 320 | 400 |
EPYC 9124 | 200 | 200 | 240 |
EPYC 9754 | 360 | 320 | 400 |
EPYC 9734 | 340 | 320 | 400 |
EPYC 7663P | 240 | 225 | 240 |
EPYC 7643P | 225 | 225 | 240 |
EPYC 7303P | 130 | 120 | 150 |
EPYC 7303 | 130 | 120 | 150 |
EPYC 7203P | 120 | 120 | 150 |
EPYC 7203 | 120 | 120 | 150 |
EPYC 9684X | 400 | 320 | 400 |
Flag description origin markings:
For questions about the meanings of these flags, please contact the tester.
For other inquiries, please contact info@spec.org
Copyright 2017-2023 Standard Performance Evaluation Corporation
Tested with SPEC CPU2017 v1.1.9.
Report generated on 2023-11-21 20:34:10 by SPEC CPU2017 flags formatter v5178.