Simple memory locking example

Simple memory locking example

This is a simple example for handling memory locking.

   #include <stdio.h>
   #include <sys/mman.h> // Needed for mlockall()
   #include <unistd.h> // needed for sysconf(int name);
   #include <malloc.h>
   #include <sys/time.h> // needed for getrusage
   #include <sys/resource.h> // needed for getrusage
   

   #define SOMESIZE (100*1024) // 100kB
   

   int main(int argc, char* argv[])
   {
       // Allocate some memory
       int i, page_size;
       char* buffer;
       struct rusage usage;
       

       // Now lock all current and future pages from preventing of being paged
       if (mlockall(MCL_CURRENT | MCL_FUTURE ))
       {
           perror("mlockall failed:");
       }
       

       page_size = sysconf(_SC_PAGESIZE);
       buffer = malloc(SOMESIZE);
       

       // Touch each page in this piece of memory to get it mapped into RAM
       for (i=0; i < SOMESIZE; i+=page_size)
       {
           // Each write to this buffer will generate a pagefault.
           // Once the pagefault is handled a page will be locked in memory and never
           // given back to the system.
           buffer[i] = 0;
           // print the number of major and minor pagefaults this application has triggered
           getrusage(RUSAGE_SELF, &usage);
           printf("Major-pagefaults:%d, Minor Pagefaults:%d\n", usage.ru_majflt, usage.ru_minflt);
       }
       // buffer is never released, or swapped, so using it from now will never lead to any pagefault
       

       //<do your RT-thing>
       

       return 0;
   }

Author/Maintainer

Remy Bohmer

Revision

Revision History
Revision 1	2008-01-15