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Subject[PATCH 4.9 06/61] lib/interval_tree_test.c: allow users to limit scope of endpoint
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit a8ec14d4f6aa8e245efacc992c8ee6ea0464ce2a ]

Add a 'max_endpoint' parameter such that users may easily limit the size
of the intervals that are randomly generated.

Link: http://lkml.kernel.org/r/20170518174936.20265-4-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
lib/interval_tree_test.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/lib/interval_tree_test.c b/lib/interval_tree_test.c
index bababcf7ffdd..222c8010bda0 100644
--- a/lib/interval_tree_test.c
+++ b/lib/interval_tree_test.c
@@ -17,6 +17,7 @@ __param(int, nsearches, 100, "Number of searches to the interval tree");
__param(int, search_loops, 1000, "Number of iterations searching the tree");
__param(bool, search_all, false, "Searches will iterate all nodes in the tree");

+__param(uint, max_endpoint, ~0, "Largest value for the interval's endpoint");

static struct rb_root root = RB_ROOT;
static struct interval_tree_node *nodes = NULL;
@@ -41,18 +42,20 @@ static void init(void)
int i;

for (i = 0; i < nnodes; i++) {
- u32 a = prandom_u32_state(&rnd);
- u32 b = prandom_u32_state(&rnd);
- if (a <= b) {
- nodes[i].start = a;
- nodes[i].last = b;
- } else {
- nodes[i].start = b;
- nodes[i].last = a;
- }
+ u32 b = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
+ u32 a = (prandom_u32_state(&rnd) >> 4) % b;
+
+ nodes[i].start = a;
+ nodes[i].last = b;
}
+
+ /*
+ * Limit the search scope to what the user defined.
+ * Otherwise we are merely measuring empty walks,
+ * which is pointless.
+ */
for (i = 0; i < nsearches; i++)
- queries[i] = prandom_u32_state(&rnd);
+ queries[i] = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
}

static int interval_tree_test_init(void)
--
2.19.1


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