From 5036880efdad976165c817dcb6a1c8c24fb16caa Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 21 Oct 2022 12:11:33 +0200 Subject: [PATCH] selftests/vm: add test to measure MADV_UNMERGEABLE performance 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 Acked-by: Peter Xu Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: Jason Gunthorpe Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Shuah Khan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- 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 0d85be2..f9eb4d6 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 @@ err_out: 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); -- 2.7.4