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authorSri Jayaramappa <sjayaram@akamai.com>2015-04-23 14:21:41 -0400
committerShuah Khan <shuahkh@osg.samsung.com>2015-05-26 15:58:06 -0600
commitbd67d5c15cc190f52eb2f2a2f6f6b800ca33d9dd (patch)
treea562c98b5e48e543e2c367a319e9af67524ec9b5 /tools/testing/selftests/vm/compaction_test.c
parentd0bd7f2ac785468ee99e24a0e7b37420e5a242e8 (diff)
downloadlinux-bd67d5c15cc190f52eb2f2a2f6f6b800ca33d9dd.tar.gz
Test compaction of mlocked memory
Commit commit 5bbe3547aa3b ("mm: allow compaction of unevictable pages") introduced a sysctl that allows userspace to enable scanning of locked pages for compaction. This patch introduces a new test which fragments main memory and attempts to allocate a number of huge pages to exercise this compaction logic. Tested on machines with up to 32 GB RAM. With the patch a much larger number of huge pages can be allocated than on the kernel without the patch. Example output: On a machine with 16 GB RAM: sudo make run_tests vm ... ----------------------- running compaction_test ----------------------- No of huge pages allocated = 3834 [PASS] ... Signed-off-by: Sri Jayaramappa <sjayaram@akamai.com> Cc: linux-kernel@vger.kernel.org Cc: linux-api@vger.kernel.org Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Eric B Munson <emunson@akamai.com> Reviewed-by: Eric B Munson <emunson@akamai.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Diffstat (limited to 'tools/testing/selftests/vm/compaction_test.c')
-rw-r--r--tools/testing/selftests/vm/compaction_test.c225
1 files changed, 225 insertions, 0 deletions
diff --git a/tools/testing/selftests/vm/compaction_test.c b/tools/testing/selftests/vm/compaction_test.c
new file mode 100644
index 000000000000..932ff577ffc0
--- /dev/null
+++ b/tools/testing/selftests/vm/compaction_test.c
@@ -0,0 +1,225 @@
+/*
+ *
+ * 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 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 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 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, sizeof(initial_nr_hugepages))
+ != strlen(initial_nr_hugepages)) {
+ perror("Failed to write 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;
+}