From: Roman Gushchin <guro@xxxxxx> Subject: kselftests: cgroup: add perpcu memory accounting test 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. Link: http://lkml.kernel.org/r/20200608230819.832349-6-guro@xxxxxx Signed-off-by: Roman Gushchin <guro@xxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Dennis Zhou <dennis@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Tobin C. Harding <tobin@xxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Waiman Long <longman@xxxxxxxxxx> Cc: Michal Koutný <mkoutny@xxxxxxxx> Cc: Bixuan Cui <cuibixuan@xxxxxxxxxx> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/cgroup/test_kmem.c | 70 ++++++++++++++++++- 1 file changed, 69 insertions(+), 1 deletion(-) --- a/tools/testing/selftests/cgroup/test_kmem.c~kselftests-cgroup-add-perpcu-memory-accounting-test +++ a/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(cons 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 @@ cleanup: 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 _
