The patch titled
Subject: selftests: vm: add COW time test for KSM pages
has been removed from the -mm tree. Its filename was
selftests-vm-add-cow-time-test-for-ksm-pages.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Zhansaya Bagdauletkyzy <zhansayabagdaulet@xxxxxxxxx>
Subject: selftests: vm: add COW time test for KSM pages
Since merged pages are copied every time they need to be modified, the
write access time is different between shared and non-shared pages. Add
ksm_cow_time() function which evaluates latency of these COW breaks.
First, 4000 pages are allocated and the time, required to modify 1 byte in
every other page, is measured. After this, the pages are merged into 2000
pairs and in each pair, 1 page is modified (i.e. they are decoupled) to
detect COW breaks. The time needed to break COW of merged pages is then
compared with performance of non-shared pages.
The test is run as follows: ./ksm_tests -C
The output:
Total size: 15 MiB
Not merged pages:
Total time: 0.002185489 s
Average speed: 3202.945 MiB/s
Merged pages:
Total time: 0.004386872 s
Average speed: 1595.670 MiB/s
Link: https://lkml.kernel.org/r/1d03ee0d1b341959d4b61672c6401d498bff5652.1629386192.git.zhansayabagdaulet@xxxxxxxxx
Signed-off-by: Zhansaya Bagdauletkyzy <zhansayabagdaulet@xxxxxxxxx>
Reviewed-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/vm/ksm_tests.c | 86 ++++++++++++++++++++++-
1 file changed, 83 insertions(+), 3 deletions(-)
--- a/tools/testing/selftests/vm/ksm_tests.c~selftests-vm-add-cow-time-test-for-ksm-pages
+++ a/tools/testing/selftests/vm/ksm_tests.c
@@ -33,7 +33,8 @@ enum ksm_test_name {
CHECK_KSM_UNMERGE,
CHECK_KSM_ZERO_PAGE_MERGE,
CHECK_KSM_NUMA_MERGE,
- KSM_MERGE_TIME
+ KSM_MERGE_TIME,
+ KSM_COW_TIME
};
static int ksm_write_sysfs(const char *file_path, unsigned long val)
@@ -98,7 +99,8 @@ static void print_help(void)
" -U (page unmerging)\n"
" -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\n");
+ " must be provided using -s option\n"
+ " -C evaluate the time required to break COW of merged pages.\n\n");
printf(" -a: specify the access protections of pages.\n"
" <prot> must be of the form [rwx].\n"
@@ -455,6 +457,77 @@ err_out:
return KSFT_FAIL;
}
+static int ksm_cow_time(int mapping, int prot, int timeout, size_t page_size)
+{
+ void *map_ptr;
+ struct timespec start_time, end_time;
+ unsigned long cow_time_ns;
+
+ /* page_count must be less than 2*page_size */
+ size_t page_count = 4000;
+
+ map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
+ if (!map_ptr)
+ return KSFT_FAIL;
+
+ if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+ perror("clock_gettime");
+ return KSFT_FAIL;
+ }
+ for (size_t i = 0; i < page_count - 1; i = i + 2)
+ memset(map_ptr + page_size * i, '-', 1);
+ if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+ perror("clock_gettime");
+ return KSFT_FAIL;
+ }
+
+ cow_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\n", (page_size * page_count) / MB);
+ printf("Not merged pages:\n");
+ printf("Total time: %ld.%09ld s\n", cow_time_ns / NSEC_PER_SEC,
+ cow_time_ns % NSEC_PER_SEC);
+ printf("Average speed: %.3f MiB/s\n\n", ((page_size * (page_count / 2)) / MB) /
+ ((double)cow_time_ns / NSEC_PER_SEC));
+
+ /* Create 2000 pairs of duplicate pages */
+ for (size_t i = 0; i < page_count - 1; i = i + 2) {
+ memset(map_ptr + page_size * i, '+', i / 2 + 1);
+ memset(map_ptr + page_size * (i + 1), '+', i / 2 + 1);
+ }
+ if (ksm_merge_pages(map_ptr, page_size * page_count, start_time, timeout))
+ goto err_out;
+
+ if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+ perror("clock_gettime");
+ goto err_out;
+ }
+ for (size_t i = 0; i < page_count - 1; i = i + 2)
+ memset(map_ptr + page_size * i, '-', 1);
+ if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+ perror("clock_gettime");
+ goto err_out;
+ }
+
+ cow_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
+ (end_time.tv_nsec - start_time.tv_nsec);
+
+ printf("Merged pages:\n");
+ printf("Total time: %ld.%09ld s\n", cow_time_ns / NSEC_PER_SEC,
+ cow_time_ns % NSEC_PER_SEC);
+ printf("Average speed: %.3f MiB/s\n", ((page_size * (page_count / 2)) / MB) /
+ ((double)cow_time_ns / NSEC_PER_SEC));
+
+ munmap(map_ptr, page_size * page_count);
+ return KSFT_PASS;
+
+err_out:
+ printf("Not OK\n");
+ munmap(map_ptr, page_size * page_count);
+ return KSFT_FAIL;
+}
+
int main(int argc, char *argv[])
{
int ret, opt;
@@ -468,7 +541,7 @@ 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:MUZNP")) != -1) {
+ while ((opt = getopt(argc, argv, "ha:p:l:z:m:s:MUZNPC")) != -1) {
switch (opt) {
case 'a':
prot = str_to_prot(optarg);
@@ -522,6 +595,9 @@ int main(int argc, char *argv[])
case 'P':
test_name = KSM_MERGE_TIME;
break;
+ case 'C':
+ test_name = KSM_COW_TIME;
+ break;
default:
return KSFT_FAIL;
}
@@ -571,6 +647,10 @@ int main(int argc, char *argv[])
ret = ksm_merge_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);
+ break;
}
if (ksm_restore(&ksm_sysfs_old)) {
_
Patches currently in -mm which might be from zhansayabagdaulet@xxxxxxxxx are
