From a47cd45a37c94bb31ccf9bf6ec3d94cbcd57d6ee Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 20 Sep 2018 11:58:09 +0100 Subject: [PATCH] drm/i915/selftests: Basic stress test for rapid context switching We need to exercise the HW and submission paths for switching contexts rapidly to check that features such as execlists' wa_tail are adequate. Plus it's an interesting baseline latency metric. v2: Check the initial request for allocation errors v3: Use finite waits for more robust handling of broken code Signed-off-by: Chris Wilson Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20180920105809.1872-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/selftests/i915_gem_context.c | 195 ++++++++++++++++++++++ 1 file changed, 195 insertions(+) diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/selftests/i915_gem_context.c index 07d700b7cb94..441a51d4aa54 100644 --- a/drivers/gpu/drm/i915/selftests/i915_gem_context.c +++ b/drivers/gpu/drm/i915/selftests/i915_gem_context.c @@ -22,6 +22,8 @@ * */ +#include + #include "../i915_selftest.h" #include "i915_random.h" #include "igt_flush_test.h" @@ -32,6 +34,198 @@ #define DW_PER_PAGE (PAGE_SIZE / sizeof(u32)) +struct live_test { + struct drm_i915_private *i915; + const char *func; + const char *name; + + unsigned int reset_count; +}; + +static int begin_live_test(struct live_test *t, + struct drm_i915_private *i915, + const char *func, + const char *name) +{ + int err; + + t->i915 = i915; + t->func = func; + t->name = name; + + err = i915_gem_wait_for_idle(i915, + I915_WAIT_LOCKED, + MAX_SCHEDULE_TIMEOUT); + if (err) { + pr_err("%s(%s): failed to idle before, with err=%d!", + func, name, err); + return err; + } + + i915->gpu_error.missed_irq_rings = 0; + t->reset_count = i915_reset_count(&i915->gpu_error); + + return 0; +} + +static int end_live_test(struct live_test *t) +{ + struct drm_i915_private *i915 = t->i915; + + if (igt_flush_test(i915, I915_WAIT_LOCKED)) + return -EIO; + + if (t->reset_count != i915_reset_count(&i915->gpu_error)) { + pr_err("%s(%s): GPU was reset %d times!\n", + t->func, t->name, + i915_reset_count(&i915->gpu_error) - t->reset_count); + return -EIO; + } + + if (i915->gpu_error.missed_irq_rings) { + pr_err("%s(%s): Missed interrupts on engines %lx\n", + t->func, t->name, i915->gpu_error.missed_irq_rings); + return -EIO; + } + + return 0; +} + +static int live_nop_switch(void *arg) +{ + const unsigned int nctx = 1024; + struct drm_i915_private *i915 = arg; + struct intel_engine_cs *engine; + struct i915_gem_context **ctx; + enum intel_engine_id id; + struct drm_file *file; + struct live_test t; + unsigned long n; + int err = -ENODEV; + + /* + * Create as many contexts as we can feasibly get away with + * and check we can switch between them rapidly. + * + * Serves as very simple stress test for submission and HW switching + * between contexts. + */ + + if (!DRIVER_CAPS(i915)->has_logical_contexts) + return 0; + + file = mock_file(i915); + if (IS_ERR(file)) + return PTR_ERR(file); + + mutex_lock(&i915->drm.struct_mutex); + + ctx = kcalloc(nctx, sizeof(*ctx), GFP_KERNEL); + if (!ctx) { + err = -ENOMEM; + goto out_unlock; + } + + for (n = 0; n < nctx; n++) { + ctx[n] = i915_gem_create_context(i915, file->driver_priv); + if (IS_ERR(ctx[n])) { + err = PTR_ERR(ctx[n]); + goto out_unlock; + } + } + + for_each_engine(engine, i915, id) { + struct i915_request *rq; + unsigned long end_time, prime; + ktime_t times[2] = {}; + + times[0] = ktime_get_raw(); + for (n = 0; n < nctx; n++) { + rq = i915_request_alloc(engine, ctx[n]); + if (IS_ERR(rq)) { + err = PTR_ERR(rq); + goto out_unlock; + } + i915_request_add(rq); + } + if (i915_request_wait(rq, + I915_WAIT_LOCKED, + HZ / 5) < 0) { + pr_err("Failed to populated %d contexts\n", nctx); + i915_gem_set_wedged(i915); + err = -EIO; + goto out_unlock; + } + + times[1] = ktime_get_raw(); + + pr_info("Populated %d contexts on %s in %lluns\n", + nctx, engine->name, ktime_to_ns(times[1] - times[0])); + + err = begin_live_test(&t, i915, __func__, engine->name); + if (err) + goto out_unlock; + + end_time = jiffies + i915_selftest.timeout_jiffies; + for_each_prime_number_from(prime, 2, 8192) { + times[1] = ktime_get_raw(); + + for (n = 0; n < prime; n++) { + rq = i915_request_alloc(engine, ctx[n % nctx]); + if (IS_ERR(rq)) { + err = PTR_ERR(rq); + goto out_unlock; + } + + /* + * This space is left intentionally blank. + * + * We do not actually want to perform any + * action with this request, we just want + * to measure the latency in allocation + * and submission of our breadcrumbs - + * ensuring that the bare request is sufficient + * for the system to work (i.e. proper HEAD + * tracking of the rings, interrupt handling, + * etc). It also gives us the lowest bounds + * for latency. + */ + + i915_request_add(rq); + } + if (i915_request_wait(rq, + I915_WAIT_LOCKED, + HZ / 5) < 0) { + pr_err("Switching between %ld contexts timed out\n", + prime); + i915_gem_set_wedged(i915); + break; + } + + times[1] = ktime_sub(ktime_get_raw(), times[1]); + if (prime == 2) + times[0] = times[1]; + + if (__igt_timeout(end_time, NULL)) + break; + } + + err = end_live_test(&t); + if (err) + goto out_unlock; + + pr_info("Switch latencies on %s: 1 = %lluns, %lu = %lluns\n", + engine->name, + ktime_to_ns(times[0]), + prime - 1, div64_u64(ktime_to_ns(times[1]), prime - 1)); + } + +out_unlock: + mutex_unlock(&i915->drm.struct_mutex); + mock_file_free(i915, file); + return err; +} + static struct i915_vma * gpu_fill_dw(struct i915_vma *vma, u64 offset, unsigned long count, u32 value) { @@ -714,6 +908,7 @@ int i915_gem_context_live_selftests(struct drm_i915_private *dev_priv) { static const struct i915_subtest tests[] = { SUBTEST(igt_switch_to_kernel_context), + SUBTEST(live_nop_switch), SUBTEST(igt_ctx_exec), SUBTEST(igt_ctx_readonly), }; -- 2.11.0