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selftests/vm: add test to measure MADV_UNMERGEABLE performance

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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.

Link: https://lkml.kernel.org/r/20221021101141.84170-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2022-10-21 12:11:33 +02:00 committed by Andrew Morton
parent c31783eeae
commit 5036880efd
1 changed files with 74 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

76
tools/testing/selftests/vm/ksm_tests.c
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@ -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);