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/*
* usemem_ksm.c exercises the ksm.c file in the mm
*
* It takes one argument 'size' and mmaps anonymous memory of 'size'
*
* into the process virtual address space.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
#define SLEEP_TIME (60)
void usage(char *name)
{
fprintf(stderr, "usage: %s SIZE\n", name);
exit(1);
}
/* calls madvise with the the specified flag */
void call_madvise (unsigned long *pointer_to_address, unsigned long size, int advise)
{
if ((madvise(pointer_to_address, size, advise)) == -1) {
fprintf(stderr, "madvise failed with error : %s\n", strerror(errno));
munmap(pointer_to_address, size);
exit(1);
}
}
int main(int argc, char *argv[])
{
/*int PS = getpagesize();*/
if (argc != 2) usage(argv[0]);
unsigned long size = atoi(argv[1]);
unsigned long *p;
p = mmap(NULL, size, PROT_READ|PROT_WRITE,
MAP_POPULATE|MAP_ANON|MAP_PRIVATE, -1, 0);
if (p == MAP_FAILED) {
fprintf(stderr, "anon mmap failed: %s\n", strerror(errno));
exit(1);
}
/* call madvise with MERGEABLE flags to enable ksm scanning */
call_madvise(p, size, MADV_MERGEABLE);
/* sleep for SLEEP_TIME seconds*/
sleep(SLEEP_TIME);
/* disable the MERGEABLE flag*/
call_madvise(p, size, MADV_UNMERGEABLE);
/* HUGEPAGE advised -- not related to ksm */
call_madvise(p, size, MADV_HUGEPAGE);
/* unmap mapped memory */
munmap(p, size);
return 0;
}
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