Using Intel® Math Kernel Library for Embedded

A simple rule, however, is this: take mandatory parts, maybe add optional parts, and wrap this in a linking group. For example (a static link line):

icc –o app.exe  … -Wl,--start-group,-Bstatic –lmkl_intel –lmkl_intel_thread –lmkl_core –liomp5 –Wl,-Bdynamic,--end-group –lpthread –lm

Usability feature

Intel® MKL

Intel® IPP

Size of statically linked executable. Many embedded applications need to have a small binary.

Large. With Intel® MKL you cannot link into your application with only one cpu branch (e.g. link in FFT optimized for SSE4.2 but not include generic SSE2).

Small. You can link in only target platform optimizations.

Threading.Harnessing cpu cores to solve tasks faster.

Intel® MKL may employ all cpu cores via internal parallelization. There is an  OpenMP runtime library dependency on the target.

Intel® IPP contains heavily vectorized single-core implementations.

Memory allocation. Embedded applications should be able to control memory used by applications: recognize and respond to shortage of memory gracefully, release memory sooner.

Intel® MKL allocates memory internally and it has its own fast memory allocator. An error is returned upon shortage of internal memory. In many cases the size of internal memory cannot be determined in advance.

Intel® IPP relies on user-allocated memory. There are functions avalable to query needed memory.

64-bit integers. With increasing embedded RAM size and cpu performance, larger problems may be processed with more than 4GB datasets. Also use of 64-bit integers matches register size and avoids redundant conversion instructions

Intel® MKL supports ILP64 interfaces. With Intel® MKL you can solve huge problems using 64-bit array indexing.

Intel® IPP uses 32-bit integers only.

Messages for embedded debugging. If a library reports an issue, the message should be human-readable, preferably localized.

Intel® MKL may occasionally print information on stdout or stderr. Message catalogues are supported (now en_US and ja_JP).

Intel® IPP does not print messages on stdout. A function to convert an error code into a human-readable message is provided. Message catalogues are supported (now en_US and ja_JP).

Runtime environment variables. All embedded execution environments support this, so embedded applications may use environment variables with no restrictions.

Intel® MKL may alter its behavior depending on environment variables, directly (e.g. MKL_DYNAMIC) or indirectly (e.g. OMP_NUM_THREADS).

Intel® IPP does not use and is not affected by environment variables.

Graceful error processing. Library shall not exit() in any case. On resource shortage library function shall return error code.

Intel® MKL may print a message and exit() if some resource is not available (e.g. a dynamic library cannot be loaded by dispatcher). Such situations are rare and are carefully documented.

Intel® IPP functions always return an error code and never call exit() or abort().

Thread Local Storage (TLS). An internal state of a library (e.g. accuracy mode), should be maintained per-thread in TLS variables.

Intel® MKL uses several global variables with Linux TLS conventions. This may cause problems on OS with incompatible TLS.

Intel® IPP does not use TLS variables.

File i/o. Many embedded devices provide a ‘disk storage’ in addition to RAM. A library may use it for temporary or persistent storage.

A few Intel® MKL functions need file i/o, namely out-of-core Pardiso.

Intel® IPP does not do file i/o.

Progress/interrupt/resume while computing large problems, an embedded application should be able to suspend execution and release resources, and later resume computation.

A few Intel® MKL functions call user-defined mkl_progress() function while doing a lengthy computation. In most cases, large computations cannot be suspended — granularization shall be done by application.

Not supported. In all cases granularization shall be done by application.

Missing symbols

Comments

Stub implementation

__strtol_internal

An alias for standard ‘strtol’ function.

#include <stdlib.h>

long __strtol_internal(char *nptr, char **endptr, int base, int group)
{ return strtol(nptr,endptr,base); }

catopen, catgets

Message catalogue functions. With this stub implementation, MKL will message in English regardless of LANG.

void *catopen(const char *name, int flag) { /*errno = EACCES*/; return (void*)(-1); }

void *catgets(void *catalog, int setno, int msgno, void *message)
{ return message; }

stderr

Reference to standard error stream.

#include <stdio.h>

#if defined(stderr)
#pragma push_macro("stderr")
#undef stderr

FILE *stderr =

#pragma pop_macro("stderr")

               stderr;

#endif