From: Thomas Hellström <[email protected]> The write_eviction subtest: - Creates a sub-cgroup and moves the test process into it. - Sets a dmem.max limit on the first VRAM region (up to 4 GiB, or the full capacity if smaller). - Fills VRAM by repeatedly creating BOs placed in VRAM, depending on card support. - Verifies that cgroup current usage is within the expected range when the limit is hit. - Lowers dmem.max in 128 MiB steps, waiting for usage to follow each reduction.
The write_eviction_interruptible subtest runs the same test with SIGCONT signals injected via igt_fork_signal_helper() and reports the number of signals received. When a signal interrupts kernel-side eviction, a small BO allocation is used to re-trigger it. Assisted-by: GitHub Copilot:claude-sonnet-4.6 Signed-off-by: Thomas Hellström <[email protected]> Signed-off-by: Thadeu Lima de Souza Cascardo <[email protected]> --- tests/cgroup_dmem.c | 149 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 149 insertions(+) diff --git a/tests/cgroup_dmem.c b/tests/cgroup_dmem.c index ba5e6a2e3deb..0d3b415acd54 100644 --- a/tests/cgroup_dmem.c +++ b/tests/cgroup_dmem.c @@ -36,9 +36,12 @@ #define BO_SIZE SZ_64M #define MAX_LIMIT ((uint64_t)4 * SZ_1G) +#define EVICT_STEP SZ_128M #define USAGE_POLL_MS 10 #define USAGE_DROP_TIMEOUT_MS 1000 +#define TEST_INTERRUPTIBLE (1 << 0) + /** * SUBTEST: simple * DESCRIPTION: @@ -61,6 +64,62 @@ * REQUIREMENTS: xe or amdgpu device with at least one VRAM region */ +/** + * SUBTEST: write_eviction + * DESCRIPTION: + * Create a dmem cgroup, move the current process into it and set the max + * device memory limit for the first VRAM region to 4 GiB. Then fill VRAM + * by creating BOs with %DRM_XE_GEM_CREATE_FLAG_DEFER_BACKING (so that the + * physical allocation is deferred until VM_BIND) and binding them into an + * LR VM until the cgroup limit is hit. Verify that the reported cgroup + * current usage is within the expected range when the error occurs. + * Finally lower the max limit in 256 MiB steps and verify that the cgroup + * usage follows. + * REQUIREMENTS: must run as root; xe device with at least one VRAM region + */ + +/** + * SUBTEST: write_eviction_interruptible + * DESCRIPTION: + * Same as write_eviction but with SIGCONT signals injected throughout via + * igt_fork_signal_helper() to verify that the dmem.max write path handles + * signal interruption correctly. A signal handler counts received signals + * and the count is reported as debug output at the end of the test. + * A signal interrupts the set-time eviction, and further eviction can be + * triggered by an explicit allocation. + * REQUIREMENTS: must run as root; xe device with at least one VRAM region + */ + +static atomic_int signal_count; +static struct sigaction sigcont_oldact; + +static void sigcont_handler(int sig) +{ + atomic_fetch_add(&signal_count, 1); + + /* Chain to the previous handler (IGT's dummy sig_handler) */ + if (sigcont_oldact.sa_handler && + sigcont_oldact.sa_handler != SIG_IGN && + sigcont_oldact.sa_handler != SIG_DFL) + sigcont_oldact.sa_handler(sig); +} + +static void install_sigcont_counter(void) +{ + struct sigaction sa; + + atomic_store(&signal_count, 0); + igt_fork_signal_helper(); + /* + * Install the counter after igt_fork_signal_helper() so our handler + * is not overwritten. Save the old handler so we can chain to it. + */ + memset(&sa, 0, sizeof(sa)); + sa.sa_handler = sigcont_handler; + sigemptyset(&sa.sa_mask); + sigaction(SIGCONT, &sa, &sigcont_oldact); +} + static uint64_t wait_for_usage_drop(struct igt_cgroup *cg, const char *region, uint64_t limit) { @@ -213,12 +272,102 @@ static void test_current(int fd, char *cg_region, unsigned int flags, const stru igt_cgroup_free(cg); } +static void test_write_eviction(int fd, char *cg_region, unsigned int flags, const struct igt_dmem_driver *drv, void *ctx) +{ + struct igt_cgroup *cg; + void **handles; + int max_bo; + uint64_t current, capacity, cg_max, limit, after; + 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); + cg_max = ALIGN_DOWN(cg_max, EVICT_STEP); + + if (flags & TEST_INTERRUPTIBLE) + install_sigcont_counter(); + + /* Create cgroup and move into it */ + cg = igt_cgroup_new("igt_cgroups_test"); + igt_cgroup_move_current(cg); + igt_cgroup_dmem_set_max(cg, cg_region, cg_max, false); + + max_bo = (cg_max / BO_SIZE) + 8; /* headroom for overcommit */ + + handles = calloc(max_bo, sizeof(handles[0])); + igt_assert_f(handles, "failed to allocate handles array"); + + allocate_vram(handles, drv, ctx, max_bo, BO_SIZE); + + 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 %"PRIu64" MiB exceeds max %"PRIu64" MiB + slack\n", + current / SZ_1M, cg_max / SZ_1M); + + /* Phase 2: lower max in 256 MiB steps, verify usage follows */ + limit = cg_max; + while (limit >= EVICT_STEP) { + + limit -= EVICT_STEP; + igt_cgroup_dmem_set_max(cg, cg_region, limit, false); + + igt_cgroup_dmem_get_current(cg, cg_region, &after); + igt_debug("Lowered max to %"PRIu64" MiB: usage = %"PRIu64" MiB\n", + limit / SZ_1M, after / SZ_1M); + + if (limit > EVICT_STEP) { + if ((flags & TEST_INTERRUPTIBLE) && after > limit) { + /* Let a new bo creation trigger eviction. */ + void *handle; + err = drv->allocate_vram(ctx, BO_SIZE / 8, &handle); + igt_assert_f(err == 0, + "Error trying to allocate more VRAM to trigger eviction."); + drv->free_vram(ctx, handle); + + igt_cgroup_dmem_get_current(cg, cg_region, &after); + igt_debug("Forced eviction max is %"PRIu64 + " MiB: usage = %"PRIu64" MiB\n", + limit / SZ_1M, after / SZ_1M); + } + + igt_assert_f(after <= limit, + "Usage %"PRIu64" MiB did not follow max %"PRIu64" MiB\n", + after / SZ_1M, limit / SZ_1M); + } + } + + if (flags & TEST_INTERRUPTIBLE) { + igt_stop_signal_helper(); + igt_info("Signals received during test: %d\n", + atomic_load(&signal_count)); + } + + /* Cleanup */ + igt_cgroup_dmem_set_max(cg, cg_region, IGT_CGROUP_DMEM_MAX, false); + 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, void *ctx); unsigned int flags; } subtests[] = { { "current", test_current, 0 }, + { "write_eviction", test_write_eviction, 0 }, + { "write_eviction_interruptible", test_write_eviction, TEST_INTERRUPTIBLE }, { } }; -- 2.47.3
