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.
Signed-off-by: Sri Jayaramappa <sjaya...@akamai.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-...@vger.kernel.org
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Eric B Munson <emun...@akamai.com>
---
tools/testing/selftests/vm/Makefile | 2 +-
tools/testing/selftests/vm/compaction_test.c | 219 ++++++++++++++++++++++++++
tools/testing/selftests/vm/run_vmtests | 12 ++
3 files changed, 232 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/vm/compaction_test.c
diff --git a/tools/testing/selftests/vm/Makefile
b/tools/testing/selftests/vm/Makefile
index a5ce953..e528836 100644
--- a/tools/testing/selftests/vm/Makefile
+++ b/tools/testing/selftests/vm/Makefile
@@ -2,7 +2,7 @@
CFLAGS = -Wall
BINARIES = hugepage-mmap hugepage-shm map_hugetlb thuge-gen hugetlbfstest
-BINARIES += transhuge-stress
+BINARIES += transhuge-stress compaction_test
all: $(BINARIES)
%: %.c
diff --git a/tools/testing/selftests/vm/compaction_test.c
b/tools/testing/selftests/vm/compaction_test.c
new file mode 100644
index 0000000..866bd71
--- /dev/null
+++ b/tools/testing/selftests/vm/compaction_test.c
@@ -0,0 +1,219 @@
+/*
+ *
+ * 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>
+
+#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)) < 0) {
+ 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 initail_nr_hugepages[10] = {0};
+ char nr_hugepages[10] = {0};
+
+ /* We want to test with 80% 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, initail_nr_hugepages, sizeof(initail_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", 1) < 0) {
+ 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) < 0) {
+ 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 1/4 th of the memory in
+ huge pages */
+ compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
+
+ if (compaction_index > 4) {
+ fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n"
+ "as huge pages\n", compaction_index);
+ goto close_fd;
+ }
+
+ if (write(fd, initail_nr_hugepages, sizeof(initail_nr_hugepages)) < 0) {
+ 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, num_maps = 0, 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) {
+ mem_fragmentable--;
+ 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;
+
+ num_maps++;
+ }
+
+ 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;
+}
diff --git a/tools/testing/selftests/vm/run_vmtests
b/tools/testing/selftests/vm/run_vmtests
index c87b681..49ece11 100755
--- a/tools/testing/selftests/vm/run_vmtests
+++ b/tools/testing/selftests/vm/run_vmtests
@@ -90,4 +90,16 @@ fi
umount $mnt
rm -rf $mnt
echo $nr_hugepgs > /proc/sys/vm/nr_hugepages
+
+echo "-----------------------"
+echo "running compaction_test"
+echo "-----------------------"
+./compaction_test
+if [ $? -ne 0 ]; then
+ echo "[FAIL]"
+ exitcode=1
+else
+ echo "[PASS]"
+fi
+
exit $exitcode
--
1.7.9.5
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