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mm/damon/tests/core-kunit: test split above max_nr_regions/2

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Add a test that exercises kdamond_split_regions() when the total region
count is already above max_nr_regions / 2, asserting that the function
still splits a fraction of the regions (makes progress) and does not
overshoot max_nr_regions.

The region size and min_region_sz are picked so the split arithmetic does
not depend on the page size.

All tests pass:
  damon: pass:31 fail:0 skip:0 total:31
  Totals: pass:31 fail:0 skip:0 total:31

Link: https://lore.kernel.org/20260626085851.70754-3-jiayuan.chen@linux.dev
Link: https://lore.kernel.org/20260629145630.134891-3-sj@kernel.org
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Signed-off-by: SJ Park <sj@kernel.org>
Reviewed-by: SJ Park <sj@kernel.org>
Cc: Shu Anzai <shu17az@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Jiayuan Chen 2026-06-29 07:56:29 -07:00 committed by Andrew Morton
parent 1a582e6e01
commit 6958d08e3a
1 changed files with 64 additions and 0 deletions
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64
mm/damon/tests/core-kunit.h
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@ -335,6 +335,69 @@ static void damon_test_split_regions_of(struct kunit *test)
damon_destroy_ctx(c);
}
/*
* When the total region count is already above max_nr_regions / 2,
* kdamond_split_regions() must keep refining the resolution by splitting a
* fraction of the regions (making progress), without exceeding
* max_nr_regions.
*/
static void damon_test_split_above_half_progresses(struct kunit *test)
{
struct damon_ctx *c;
struct damon_target *t;
struct damon_region *r;
unsigned long start;
unsigned int nr_before, nr_after, i;
const unsigned int nr_init = 760;
const unsigned long region_sz = 100;
c = damon_new_ctx();
if (!c)
kunit_skip(test, "ctx alloc fail");
/* Keep the split arithmetic independent of the page size */
c->min_region_sz = 1;
c->attrs.min_nr_regions = 10;
c->attrs.max_nr_regions = 1500;
t = damon_new_target();
if (!t) {
damon_destroy_ctx(c);
kunit_skip(test, "target alloc fail");
}
for (i = 0; i < nr_init; i++) {
start = i * region_sz;
r = damon_new_region(start, start + region_sz);
if (!r) {
damon_free_target(t);
damon_destroy_ctx(c);
kunit_skip(test, "region alloc fail");
}
r->nr_accesses = (i & 1) ? 0 : 100;
r->age = 5;
damon_add_region(r, t);
}
damon_add_target(c, t);
nr_before = damon_nr_regions(t);
/* Above max_nr_regions / 2, so the blanket-split path is skipped */
KUNIT_EXPECT_GT(test, (unsigned long)nr_before,
c->attrs.max_nr_regions / 2);
kdamond_split_regions(c);
nr_after = damon_nr_regions(t);
/* Still made progress ... */
KUNIT_EXPECT_GT(test, nr_after, nr_before);
/* ... but did not overshoot the configured maximum */
KUNIT_EXPECT_LE(test, (unsigned long)nr_after,
c->attrs.max_nr_regions);
damon_destroy_ctx(c);
}
static void damon_test_ops_registration(struct kunit *test)
{
struct damon_ctx *c = damon_new_ctx();
@ -1491,6 +1554,7 @@ static struct kunit_case damon_test_cases[] = {
KUNIT_CASE(damon_test_merge_two),
KUNIT_CASE(damon_test_merge_regions_of),
KUNIT_CASE(damon_test_split_regions_of),
KUNIT_CASE(damon_test_split_above_half_progresses),
KUNIT_CASE(damon_test_ops_registration),
KUNIT_CASE(damon_test_set_regions),
KUNIT_CASE(damon_test_nr_accesses_to_accesses_bp),