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Commit 061ef393 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Linus Torvalds
Browse files

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: default avatarMatthew Wilcox <willy@infradead.org>
Tested-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6df5ee78

tools/testing/radix-tree/iteration_check.c

+7 −4
Original line number Diff line number Diff line
@@ -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);

tools/testing/radix-tree/main.c

+7 −2
Original line number Diff line number Diff line
@@ -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();