Resolve Memory Access Issue
Edit the source code to resolve the memory access issue that was identified in the previous step. Then, recompile the matrix application. These steps are explained in detail, but before you proceed, make note of the optimization setting for your compiler.
Compiler Optimization
This tutorial uses the Intel® oneAPI DPC++/C++ Compiler. Your choice of a different compiler can affect your results and your workflow.
The procedures in this section call for the compiler optimization level to be set to Maximum Optimization (Favor Speed) (-O2).
Edit and Recompile the Sample Code
To edit and recompile the sample code using the Intel® oneAPI DPC++/C++ Compiler:
In the /opt/intel/oneapi/compiler/latest/env folder, set the environment variables for the compiler. Run this command:
source env.vars
Locate the matrix sample application folder on your machine. By default, it is placed in:
$HOME/intel/vtune/samples/matrix
Using a text editor of your choice, open the Makefile in the ../matrix/linux/ folder.
Change line 41 from:
ICC = icc
to
ICC = icx
Change line 42 from:
CFLAGS = -g -O3 -fno-asm
to
CFLAGS = -g -O2
Change line 43 from:
OPTFLAGS = -xSSE3
to
OPTFLAGS =
Save and close the Makefile.
Open the multiply.h header file located in ../matrix/src folder with a text editor.
Change line 36 from:
#define MULTIPLY multiply1
to
#define MULTIPLY multiply2
This changes the program to use the multiply2 function from the multiply.c source file. This change implements the loop interchange technique that resolves the memory access problem.
Save and close the multiply.h file.
Open the ../matrix/linux folder.
Recompile the application. Run this command:
make icc