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// SPDX-License-Identifier: GPL-2.0
/*
*
* A test for the patch "Allow compaction of unevictable pages".
* With this patch we should be able to allocate at least 1/4
* of RAM in huge pages. Without the patch much less is
* allocated.
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#define MAP_SIZE 1048576
struct map_list {
void *map;
struct map_list *next;
};
int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
{
char buffer[256] = {0};
char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
FILE *cmdfile = popen(cmd, "r");
if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
perror("Failed to read meminfo\n");
return -1;
}
pclose(cmdfile);
*memfree = atoll(buffer);
cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
cmdfile = popen(cmd, "r");
if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
perror("Failed to read meminfo\n");
return -1;
}
pclose(cmdfile);
*hugepagesize = atoll(buffer);
return 0;
}
int prereq(void)
{
char allowed;
int fd;
fd = open("/proc/sys/vm/compact_unevictable_allowed",
O_RDONLY | O_NONBLOCK);
if (fd < 0) {
perror("Failed to open\n"
"/proc/sys/vm/compact_unevictable_allowed\n");
return -1;
}
if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
perror("Failed to read from\n"
"/proc/sys/vm/compact_unevictable_allowed\n");
close(fd);
return -1;
}
close(fd);
if (allowed == '1')
return 0;
return -1;
}
int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
{
int fd;
int compaction_index = 0;
char initial_nr_hugepages[10] = {0};
char nr_hugepages[10] = {0};
/* We want to test with 80% of available memory. Else, OOM killer comes
in to play */
mem_free = mem_free * 0.8;
fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
if (fd < 0) {
perror("Failed to open /proc/sys/vm/nr_hugepages");
return -1;
}
if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
perror("Failed to read from /proc/sys/vm/nr_hugepages");
goto close_fd;
}
/* Start with the initial condition of 0 huge pages*/
if (write(fd, "0", sizeof(char)) != sizeof(char)) {
perror("Failed to write 0 to /proc/sys/vm/nr_hugepages\n");
goto close_fd;
}
lseek(fd, 0, SEEK_SET);
/* Request a large number of huge pages. The Kernel will allocate
as much as it can */
if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
perror("Failed to write 100000 to /proc/sys/vm/nr_hugepages\n");
goto close_fd;
}
lseek(fd, 0, SEEK_SET);
if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
perror("Failed to re-read from /proc/sys/vm/nr_hugepages\n");
goto close_fd;
}
/* We should have been able to request at least 1/3 rd of the memory in
huge pages */
compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
if (compaction_index > 3) {
printf("No of huge pages allocated = %d\n",
(atoi(nr_hugepages)));
fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n"
"as huge pages\n", compaction_index);
goto close_fd;
}
printf("No of huge pages allocated = %d\n",
(atoi(nr_hugepages)));
if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
!= strlen(initial_nr_hugepages)) {
perror("Failed to write value to /proc/sys/vm/nr_hugepages\n");
goto close_fd;
}
close(fd);
return 0;
close_fd:
close(fd);
printf("Not OK. Compaction test failed.");
return -1;
}
int main(int argc, char **argv)
{
struct rlimit lim;
struct map_list *list, *entry;
size_t page_size, i;
void *map = NULL;
unsigned long mem_free = 0;
unsigned long hugepage_size = 0;
unsigned long mem_fragmentable = 0;
if (prereq() != 0) {
printf("Either the sysctl compact_unevictable_allowed is not\n"
"set to 1 or couldn't read the proc file.\n"
"Skipping the test\n");
return 0;
}
lim.rlim_cur = RLIM_INFINITY;
lim.rlim_max = RLIM_INFINITY;
if (setrlimit(RLIMIT_MEMLOCK, &lim)) {
perror("Failed to set rlimit:\n");
return -1;
}
page_size = getpagesize();
list = NULL;
if (read_memory_info(&mem_free, &hugepage_size) != 0) {
printf("ERROR: Cannot read meminfo\n");
return -1;
}
mem_fragmentable = mem_free * 0.8 / 1024;
while (mem_fragmentable > 0) {
map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
if (map == MAP_FAILED)
break;
entry = malloc(sizeof(struct map_list));
if (!entry) {
munmap(map, MAP_SIZE);
break;
}
entry->map = map;
entry->next = list;
list = entry;
/* Write something (in this case the address of the map) to
* ensure that KSM can't merge the mapped pages
*/
for (i = 0; i < MAP_SIZE; i += page_size)
*(unsigned long *)(map + i) = (unsigned long)map + i;
mem_fragmentable--;
}
for (entry = list; entry != NULL; entry = entry->next) {
munmap(entry->map, MAP_SIZE);
if (!entry->next)
break;
entry = entry->next;
}
if (check_compaction(mem_free, hugepage_size) == 0)
return 0;
return -1;
}
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