Hi Thadeu,
On 2026-07-02 at 10:00:58 -0300, Thadeu Lima de Souza Cascardo wrote:
> Based on the work of Thomas Hellström to test dmem.max eviction, add a test
> for dmem.current usage after allocations and setting dmem.max.
>
> Create a dmem cgroup, allocate close to capacity (or at most 4GiB), check
> current usage is within a small slack of the expected allocation. Then,
> set max to a small value and check allocations and current usage are
> limited to the max set. Set max to 0, then check no allocations are
> allowed and current usage is also within the slack. After each allocation,
> release memory and check current usage has gone down.
>
> Signed-off-by: Thadeu Lima de Souza Cascardo <[email protected]>
> ---
> tests/dmem_cgroups.c | 245 +++++++++++++++++++++++++++++++++++++++++++
Why two tests? dmesm_cgropus and cgroups_dmem?
Why not only one? This is confusing.
Regards,
Kamil
> tests/meson.build | 1 +
> 2 files changed, 246 insertions(+)
> create mode 100644 tests/dmem_cgroups.c
>
> diff --git a/tests/dmem_cgroups.c b/tests/dmem_cgroups.c
> new file mode 100644
> index 000000000000..da2475a14ff9
> --- /dev/null
> +++ b/tests/dmem_cgroups.c
> @@ -0,0 +1,245 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2026 Intel Corporation
> + */
> +
> +/**
> + * TEST: dmem_cgroups
> + * DESCRIPTION: Tests exercising the dmem cgroup controller on devices.
> + * Category: Core
> + * Mega feature: General Core features
> + * Sub-category: cgroup
> + * FUNCTIONALITY: cgroup dmem controller
> + */
> +
> +#include <errno.h>
> +#include <signal.h>
> +#include <stdatomic.h>
> +#include <stdint.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +#include "drmtest.h"
> +#include "igt.h"
> +#include "igt_aux.h"
> +#include "igt_cgroup.h"
> +#include "igt_dmem_driver.h"
> +
> +#define BO_SIZE SZ_64M
> +#define MAX_LIMIT ((uint64_t)4 * SZ_1G)
> +#define USAGE_SLACK SZ_4M /* tolerance above the set max
> */
> +#define USAGE_POLL_MS 10
> +#define USAGE_DROP_TIMEOUT_MS 1000
> +
> +/**
> + * SUBTEST: current
> + * DESCRIPTION:
> + * Create a dmem cgroup, allocate close to capacity (or at most 4GiB),
> + * check current usage is within a small slack of the expected allocation.
> + * Then, set max to a small value and check allocations and current usage
> + * are limited to the max set.
> + * Set max to 0, then check no allocations are allowed and current usage
> + * is also within the slack.
> + * After each allocation, release memory and check current usage has gone
> + * down.
> + * REQUIREMENTS: xe or amdgpu device with at least one VRAM region
> + */
> +
> +static uint64_t wait_for_usage_drop(struct igt_cgroup *cg, const char
> *region,
> + uint64_t limit)
> +{
> + uint64_t current;
> + unsigned int elapsed = 0;
> +
> + do {
> + igt_cgroup_dmem_get_current(cg, region, ¤t);
> + if (current <= limit)
> + return current;
> + usleep(USAGE_POLL_MS * 1000);
> + elapsed += USAGE_POLL_MS;
> + } while (elapsed < USAGE_DROP_TIMEOUT_MS);
> +
> + return current;
> +}
> +
> +static int allocate_vram(const struct igt_dmem_driver *drv, void *ctx, int
> fd, int max_bo, size_t len)
> +{
> + int n_bo, err = 0;
> + for (n_bo = 0; n_bo < max_bo; n_bo++) {
> + err = drv->allocate_vram(ctx, n_bo, len);
> + if (err)
> + break;
> + }
> + /* These are expected failures we can ignore. */
> + if (err == -ENOMEM || err == -ENOSPC)
> + err = 0;
> + return err ?: n_bo;
> +}
> +
> +static void free_vram(const struct igt_dmem_driver *drv, void *ctx, int
> max_bo)
> +{
> + int i;
> + for (i = 0; i < max_bo; i++)
> + drv->free_vram(ctx, i);
> +}
> +
> +static void test_current(int fd, char *cg_region, unsigned int flags, const
> struct igt_dmem_driver *drv)
> +{
> + struct igt_cgroup *cg;
> + void *ctx;
> + uint64_t current, capacity, cg_max;
> + int n_bo = 0, max_bo;
> + int err;
> +
> + igt_cgroup_dmem_get_capacity(cg_region, &capacity);
> + igt_require_f(capacity >= 4 * BO_SIZE,
> + "VRAM capacity (%"PRIu64" MiB) too small to test\n",
> + capacity / SZ_1M);
> +
> + /*
> + * Use up to 4 GiB, or the full capacity if the device has less.
> + * Leave one BO_SIZE worth of headroom so the device isn't completely
> + * exhausted before the cgroup limit is hit.
> + */
> + cg_max = min(MAX_LIMIT, capacity - BO_SIZE - USAGE_SLACK);
> + cg_max = ALIGN_DOWN(cg_max, BO_SIZE);
> +
> + /* Create cgroup and move into it */
> + cg = igt_cgroup_new("igt_cgroups_test");
> + igt_cgroup_move_current(cg);
> +
> + max_bo = cg_max / BO_SIZE;
> +
> + err = drv->init(&ctx, fd, max_bo);
> + igt_assert_f(!err, "Failed to initialize driver");
> +
> + n_bo = allocate_vram(drv, ctx, fd, max_bo, BO_SIZE);
> + igt_assert_f(n_bo > 0, "failed to allocate VRAM\n");
> +
> + igt_cgroup_dmem_get_current(cg, cg_region, ¤t);
> + igt_debug("After fill: cgroup current = %"PRIu64" MiB, "
> + "max = %"PRIu64" MiB\n",
> + current / SZ_1M, cg_max / SZ_1M);
> + igt_assert_f(current < cg_max + USAGE_SLACK && current > cg_max -
> USAGE_SLACK,
> + "current usage (%"PRIu64" MiB) is not within margin of
> allocation (%"PRIu64" MiB)\n",
> + current / SZ_1M, cg_max / SZ_1M);
> +
> + free_vram(drv, ctx, n_bo);
> + wait_for_usage_drop(cg, cg_region, USAGE_SLACK);
> +
> + igt_cgroup_dmem_get_current(cg, cg_region, ¤t);
> + igt_debug("After free: cgroup current = %"PRIu64" MiB, "
> + "max = %"PRIu64" MiB\n",
> + current / SZ_1M, cg_max / SZ_1M);
> + igt_assert_f(current < USAGE_SLACK,
> + "current usage (%"PRIu64" MiB) is not within margin (%d
> MiB)\n",
> + current / SZ_1M, USAGE_SLACK / SZ_1M);
> +
> + /* Allow for a slack as there might be some extra pages allocated. */
> + igt_cgroup_dmem_set_max(cg, cg_region, 2 * BO_SIZE + USAGE_SLACK,
> false);
> +
> + n_bo = allocate_vram(drv, ctx, fd, max_bo, BO_SIZE);
> + igt_assert_f(n_bo > 0, "failed to allocate VRAM\n");
> +
> + igt_cgroup_dmem_get_current(cg, cg_region, ¤t);
> + igt_debug("After fill: cgroup current = %"PRIu64" MiB, "
> + "max = %"PRIu64" MiB\n",
> + current / SZ_1M, cg_max / SZ_1M);
> + igt_assert_f(current < 2 * BO_SIZE + USAGE_SLACK && current > 2 *
> BO_SIZE - USAGE_SLACK,
> + "current usage (%"PRIu64" MiB) is not within margin of
> allocation (%"PRIu64" MiB)\n",
> + current / SZ_1M, cg_max / SZ_1M);
> +
> + free_vram(drv, ctx, n_bo);
> + wait_for_usage_drop(cg, cg_region, USAGE_SLACK);
> +
> + igt_cgroup_dmem_get_current(cg, cg_region, ¤t);
> + igt_debug("After free: cgroup current = %"PRIu64" MiB, "
> + "max = %"PRIu64" MiB\n",
> + current / SZ_1M, cg_max / SZ_1M);
> + igt_assert_f(current < USAGE_SLACK,
> + "current usage (%"PRIu64" MiB) is not within margin (%d
> MiB)\n",
> + current / SZ_1M, USAGE_SLACK / SZ_1M);
> +
> + igt_cgroup_dmem_set_max(cg, cg_region, USAGE_SLACK, false);
> +
> + n_bo = allocate_vram(drv, ctx, fd, max_bo, BO_SIZE);
> + igt_assert_f(n_bo != -ENOMEM, "VRAM allocation succeeded despite max
> set to 0\n");
> +
> + igt_cgroup_dmem_get_current(cg, cg_region, ¤t);
> + igt_debug("After fill: cgroup current = %"PRIu64" MiB, "
> + "max = %"PRIu64" MiB\n",
> + current / SZ_1M, cg_max / SZ_1M);
> + igt_assert_f(current < USAGE_SLACK,
> + "current usage (%"PRIu64" MiB) is not within margin\n",
> + current / SZ_1M);
> +
> + if (n_bo > 0)
> + free_vram(drv, ctx, n_bo);
> + wait_for_usage_drop(cg, cg_region, USAGE_SLACK);
> +
> + igt_cgroup_dmem_get_current(cg, cg_region, ¤t);
> + igt_debug("After free: cgroup current = %"PRIu64" MiB, "
> + "max = %"PRIu64" MiB\n",
> + current / SZ_1M, cg_max / SZ_1M);
> + igt_assert_f(current < USAGE_SLACK,
> + "current usage (%"PRIu64" MiB) is not within margin (%d
> MiB)\n",
> + current / SZ_1M, USAGE_SLACK / SZ_1M);
> +
> + drv->deinit(ctx);
> + igt_cgroup_free(cg);
> +}
> +
> +static const struct {
> + const char *name;
> + void (*test_fn)(int fd, char *cg_region, unsigned int flags, const
> struct igt_dmem_driver *drv);
> + unsigned int flags;
> +} subtests[] = {
> + { "current", test_current, 0 },
> + { }
> +};
> +
> +static const struct {
> + int driver_flag;
> + const struct igt_dmem_driver *driver;
> +} drivers[] = {
> + { DRIVER_XE, &xe_dmem_driver },
> + { DRIVER_AMDGPU, &amdgpu_dmem_driver },
> + { },
> +};
> +
> +int igt_main()
> +{
> + igt_fixture() {
> + igt_require_f(getuid() == 0, "Test requires root\n");
> + /* Check dmem cgroup controller is available before doing
> anything else */
> + igt_require_f(igt_cgroup_dmem_available(),
> + "dmem cgroup controller not available (no cgroup
> v2 or no registered regions)\n");
> +
> + }
> +
> + for (int d = 0; drivers[d].driver; d++) {
> + igt_subtest_group() {
> + int fd = -1;
> + char *cg_region;
> + igt_fixture() {
> + fd = drm_open_driver(drivers[d].driver_flag);
> + igt_require_f(fd >= 0,
> + "No %s device found, skipping\n",
> + drivers[d].driver->name);
> + cg_region =
> drivers[d].driver->get_region_name(fd);
> + igt_require_f(cg_region, "Region not tracked by
> dmem cgroup controller\n");
> + }
> +
> + for (int i = 0; subtests[i].name; i++)
> + igt_subtest_f("%s-%s", drivers[d].driver->name,
> subtests[i].name)
> + subtests[i].test_fn(fd, cg_region,
> subtests[i].flags, drivers[d].driver);
> +
> + igt_fixture() {
> + if (fd >= 0)
> + drm_close_driver(fd);
> + free(cg_region);
> + }
> + }
> + }
> +}
> diff --git a/tests/meson.build b/tests/meson.build
> index 88a0ce224432..dfdaab41825a 100644
> --- a/tests/meson.build
> +++ b/tests/meson.build
> @@ -11,6 +11,7 @@ test_progs = [
> 'core_sysfs',
> 'dmabuf',
> 'dmabuf_sync_file',
> + 'dmem_cgroups',
> 'device_reset',
> 'dumb_buffer',
> 'drm_buddy',
> --
> 2.47.3
>
