Add a simple test to check the percpu memory accounting.
The test creates a cgroup tree with 1000 child cgroups
and checks values of memory.current and memory.stat::percpu.
Signed-off-by: Roman Gushchin <guro@xxxxxx>
---
tools/testing/selftests/cgroup/test_kmem.c | 70 +++++++++++++++++++++-
1 file changed, 69 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c
index 5224dae216e5..0941aa16157e 100644
--- a/tools/testing/selftests/cgroup/test_kmem.c
+++ b/tools/testing/selftests/cgroup/test_kmem.c
@@ -18,6 +18,15 @@
#include "cgroup_util.h"
+/*
+ * Memory cgroup charging and vmstat data aggregation is performed using
+ * percpu batches 32 pages big (look at MEMCG_CHARGE_BATCH). So the maximum
+ * discrepancy between charge and vmstat entries is number of cpus multiplied
+ * by 32 pages multiplied by 2.
+ */
+#define MAX_VMSTAT_ERROR (4096 * 32 * 2 * get_nprocs())
+
+
static int alloc_dcache(const char *cgroup, void *arg)
{
unsigned long i;
@@ -180,7 +189,7 @@ static int test_kmem_memcg_deletion(const char *root)
goto cleanup;
sum = slab + anon + file + kernel_stack;
- if (abs(sum - current) < 4096 * 32 * 2 * get_nprocs()) {
+ if (abs(sum - current) < MAX_VMSTAT_ERROR) {
ret = KSFT_PASS;
} else {
printf("memory.current = %ld\n", current);
@@ -331,6 +340,64 @@ static int test_kmem_dead_cgroups(const char *root)
return ret;
}
+/*
+ * This test creates a sub-tree with 1000 memory cgroups.
+ * Then it checks that the memory.current on the parent level
+ * is greater than 0 and approximates matches the percpu value
+ * from memory.stat.
+ */
+static int test_percpu_basic(const char *root)
+{
+ int ret = KSFT_FAIL;
+ char *parent, *child;
+ long current, percpu;
+ int i;
+
+ parent = cg_name(root, "percpu_basic_test");
+ if (!parent)
+ goto cleanup;
+
+ if (cg_create(parent))
+ goto cleanup;
+
+ if (cg_write(parent, "cgroup.subtree_control", "+memory"))
+ goto cleanup;
+
+ for (i = 0; i < 1000; i++) {
+ child = cg_name_indexed(parent, "child", i);
+ if (!child)
+ return -1;
+
+ if (cg_create(child))
+ goto cleanup_children;
+
+ free(child);
+ }
+
+ current = cg_read_long(parent, "memory.current");
+ percpu = cg_read_key_long(parent, "memory.stat", "percpu ");
+
+ if (current > 0 && percpu > 0 && abs(current - percpu) <
+ MAX_VMSTAT_ERROR)
+ ret = KSFT_PASS;
+ else
+ printf("memory.current %ld\npercpu %ld\n",
+ current, percpu);
+
+cleanup_children:
+ for (i = 0; i < 1000; i++) {
+ child = cg_name_indexed(parent, "child", i);
+ cg_destroy(child);
+ free(child);
+ }
+
+cleanup:
+ cg_destroy(parent);
+ free(parent);
+
+ return ret;
+}
+
#define T(x) { x, #x }
struct kmem_test {
int (*fn)(const char *root);
@@ -341,6 +408,7 @@ struct kmem_test {
T(test_kmem_proc_kpagecgroup),
T(test_kmem_kernel_stacks),
T(test_kmem_dead_cgroups),
+ T(test_percpu_basic),
};
#undef T
--
2.25.4
