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/*
* code for allocating hugepages using shared memory segment
*/
#include "usemem_hugepages.h"
#include <stdio.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
/* Initialize seg_id to 0 */
int seg_id = 0;
/* Set the shared memory segment to destruction */
void shm_free(int seg_id)
{
if (seg_id < 0) {
perror("Invalid seg_id\n");
exit(1);
} else
shmctl(seg_id, IPC_RMID, NULL);
}
/* Allocate huge pages using shm segment */
unsigned long *allocate_hugepage_segment(unsigned long bytes)
{
unsigned long *p;
if (!bytes) {
perror("invalid size\n");
exit(1);
}
/* create a shared sys V IPC shared object of size "bytes"*/
if ((seg_id = shmget(IPC_PRIVATE, bytes, SHM_HUGETLB | IPC_CREAT | SHM_R |SHM_W)) == -1) {
/* Check if the shmget call was successful */
fprintf(stderr, "Error creating shared segment: %s \n", strerror(errno));
exit(1);
} else { /* Attach the shared memory to callers virtual address space */
/* Check if the attachment was successful */
if ((p = shmat(seg_id, NULL, 0)) == (void *) -1) {
fprintf(stderr, "Error attaching shared memory: %s \n", strerror(errno));
shm_free(seg_id);
exit(1);
}
}
return p;
}
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