From 061ef3936b16edc8f779d403d569392505665ed5 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Wed, 14 Dec 2016 15:08:08 -0800 Subject: [PATCH] radix tree test suite: make runs more reproducible Instead of reseeding the random number generator every time around the loop in big_gang_check(), seed it at the beginning of execution. Use rand_r() and an independent base seed for each thread in iteration_test() so they don't stomp all over each others state. Since this particular test depends on the kernel scheduler, the iteration test can't be reproduced based purely on the random seed, but at least it won't pollute the other tests. Print the seed, and allow the seed to be specified so that a run which hits a problem can be reproduced. Link: http://lkml.kernel.org/r/1480369871-5271-41-git-send-email-mawilcox@linuxonhyperv.com Signed-off-by: Matthew Wilcox Tested-by: Kirill A. Shutemov Cc: Konstantin Khlebnikov Cc: Ross Zwisler Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- tools/testing/radix-tree/iteration_check.c | 11 +++++++---- tools/testing/radix-tree/main.c | 9 +++++++-- 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/tools/testing/radix-tree/iteration_check.c b/tools/testing/radix-tree/iteration_check.c index 9adb8e7415a6..11d570c3fc83 100644 --- a/tools/testing/radix-tree/iteration_check.c +++ b/tools/testing/radix-tree/iteration_check.c @@ -20,6 +20,7 @@ #define TAG 0 static pthread_mutex_t tree_lock = PTHREAD_MUTEX_INITIALIZER; static pthread_t threads[NUM_THREADS]; +static unsigned int seeds[3]; RADIX_TREE(tree, GFP_KERNEL); bool test_complete; @@ -71,7 +72,7 @@ static void *tagged_iteration_fn(void *arg) continue; } - if (rand() % 50 == 0) + if (rand_r(&seeds[0]) % 50 == 0) slot = radix_tree_iter_next(&iter); } rcu_read_unlock(); @@ -111,7 +112,7 @@ static void *untagged_iteration_fn(void *arg) continue; } - if (rand() % 50 == 0) + if (rand_r(&seeds[1]) % 50 == 0) slot = radix_tree_iter_next(&iter); } rcu_read_unlock(); @@ -129,7 +130,7 @@ static void *remove_entries_fn(void *arg) while (!test_complete) { int pgoff; - pgoff = rand() % 100; + pgoff = rand_r(&seeds[2]) % 100; pthread_mutex_lock(&tree_lock); item_delete(&tree, pgoff); @@ -146,9 +147,11 @@ void iteration_test(void) printf("Running iteration tests for 10 seconds\n"); - srand(time(0)); test_complete = false; + for (i = 0; i < 3; i++) + seeds[i] = rand(); + if (pthread_create(&threads[0], NULL, tagged_iteration_fn, NULL)) { perror("pthread_create"); exit(1); diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c index 52ce1eab0fd3..2eb694994497 100644 --- a/tools/testing/radix-tree/main.c +++ b/tools/testing/radix-tree/main.c @@ -67,7 +67,6 @@ void big_gang_check(bool long_run) for (i = 0; i < (long_run ? 1000 : 3); i++) { __big_gang_check(); - srand(time(0)); printf("%d ", i); fflush(stdout); } @@ -329,12 +328,18 @@ int main(int argc, char **argv) { bool long_run = false; int opt; + unsigned int seed = time(NULL); - while ((opt = getopt(argc, argv, "l")) != -1) { + while ((opt = getopt(argc, argv, "ls:")) != -1) { if (opt == 'l') long_run = true; + else if (opt == 's') + seed = strtoul(optarg, NULL, 0); } + printf("random seed %u\n", seed); + srand(seed); + rcu_register_thread(); radix_tree_init(); -- 2.20.1