Let's add a test to measure performance of KSM breaking not triggered
via COW, but triggered by disabling KSM on an area filled with KSM pages
via MADV_UNMERGEABLE.
Acked-by: Peter Xu <peterx@xxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
tools/testing/selftests/vm/ksm_tests.c | 76 +++++++++++++++++++++++++-
1 file changed, 74 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
index 0d85be2350fa..f9eb4d67e0dd 100644
--- a/tools/testing/selftests/vm/ksm_tests.c
+++ b/tools/testing/selftests/vm/ksm_tests.c
@@ -40,6 +40,7 @@ enum ksm_test_name {
CHECK_KSM_NUMA_MERGE,
KSM_MERGE_TIME,
KSM_MERGE_TIME_HUGE_PAGES,
+ KSM_UNMERGE_TIME,
KSM_COW_TIME
};
@@ -108,7 +109,10 @@ static void print_help(void)
" -P evaluate merging time and speed.\n"
" For this test, the size of duplicated memory area (in MiB)\n"
" must be provided using -s option\n"
- " -H evaluate merging time and speed of area allocated mostly with huge pages\n"
+ " -H evaluate merging time and speed of area allocated mostly with huge pages\n"
+ " For this test, the size of duplicated memory area (in MiB)\n"
+ " must be provided using -s option\n"
+ " -D evaluate unmerging time and speed when disabling KSM.\n"
" For this test, the size of duplicated memory area (in MiB)\n"
" must be provided using -s option\n"
" -C evaluate the time required to break COW of merged pages.\n\n");
@@ -188,6 +192,16 @@ static int ksm_merge_pages(void *addr, size_t size, struct timespec start_time,
return 0;
}
+static int ksm_unmerge_pages(void *addr, size_t size,
+ struct timespec start_time, int timeout)
+{
+ if (madvise(addr, size, MADV_UNMERGEABLE)) {
+ perror("madvise");
+ return 1;
+ }
+ return 0;
+}
+
static bool assert_ksm_pages_count(long dupl_page_count)
{
unsigned long max_page_sharing, pages_sharing, pages_shared;
@@ -560,6 +574,53 @@ static int ksm_merge_time(int mapping, int prot, int timeout, size_t map_size)
return KSFT_FAIL;
}
+static int ksm_unmerge_time(int mapping, int prot, int timeout, size_t map_size)
+{
+ void *map_ptr;
+ struct timespec start_time, end_time;
+ unsigned long scan_time_ns;
+
+ map_size *= MB;
+
+ map_ptr = allocate_memory(NULL, prot, mapping, '*', map_size);
+ if (!map_ptr)
+ return KSFT_FAIL;
+ if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+ perror("clock_gettime");
+ goto err_out;
+ }
+ if (ksm_merge_pages(map_ptr, map_size, start_time, timeout))
+ goto err_out;
+
+ if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+ perror("clock_gettime");
+ goto err_out;
+ }
+ if (ksm_unmerge_pages(map_ptr, map_size, start_time, timeout))
+ goto err_out;
+ if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+ perror("clock_gettime");
+ goto err_out;
+ }
+
+ scan_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
+ (end_time.tv_nsec - start_time.tv_nsec);
+
+ printf("Total size: %lu MiB\n", map_size / MB);
+ printf("Total time: %ld.%09ld s\n", scan_time_ns / NSEC_PER_SEC,
+ scan_time_ns % NSEC_PER_SEC);
+ printf("Average speed: %.3f MiB/s\n", (map_size / MB) /
+ ((double)scan_time_ns / NSEC_PER_SEC));
+
+ munmap(map_ptr, map_size);
+ return KSFT_PASS;
+
+err_out:
+ printf("Not OK\n");
+ munmap(map_ptr, map_size);
+ return KSFT_FAIL;
+}
+
static int ksm_cow_time(int mapping, int prot, int timeout, size_t page_size)
{
void *map_ptr;
@@ -644,7 +705,7 @@ int main(int argc, char *argv[])
bool merge_across_nodes = KSM_MERGE_ACROSS_NODES_DEFAULT;
long size_MB = 0;
- while ((opt = getopt(argc, argv, "ha:p:l:z:m:s:MUZNPCH")) != -1) {
+ while ((opt = getopt(argc, argv, "ha:p:l:z:m:s:MUZNPCHD")) != -1) {
switch (opt) {
case 'a':
prot = str_to_prot(optarg);
@@ -701,6 +762,9 @@ int main(int argc, char *argv[])
case 'H':
test_name = KSM_MERGE_TIME_HUGE_PAGES;
break;
+ case 'D':
+ test_name = KSM_UNMERGE_TIME;
+ break;
case 'C':
test_name = KSM_COW_TIME;
break;
@@ -762,6 +826,14 @@ int main(int argc, char *argv[])
ret = ksm_merge_hugepages_time(MAP_PRIVATE | MAP_ANONYMOUS, prot,
ksm_scan_limit_sec, size_MB);
break;
+ case KSM_UNMERGE_TIME:
+ if (size_MB == 0) {
+ printf("Option '-s' is required.\n");
+ return KSFT_FAIL;
+ }
+ ret = ksm_unmerge_time(MAP_PRIVATE | MAP_ANONYMOUS, prot,
+ ksm_scan_limit_sec, size_MB);
+ break;
case KSM_COW_TIME:
ret = ksm_cow_time(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
page_size);
--
2.37.3
