We [will] expose various per-engine scheduling controls. One of which,
'heartbeat_duration_ms', defines how often we send a heartbeat down the
engine to check upon the health of the engine. If a heartbeat does not
complete within the interval (or two), the engine is declared hung.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
 tests/Makefile.sources                |   3 +
 tests/i915/sysfs_heartbeat_interval.c | 446 ++++++++++++++++++++++++++
 tests/intel-ci/blacklist.txt          |   1 +
 tests/meson.build                     |   1 +
 4 files changed, 451 insertions(+)
 create mode 100644 tests/i915/sysfs_heartbeat_interval.c

diff --git a/tests/Makefile.sources b/tests/Makefile.sources
index c1711b336..7b1f8194d 100644
--- a/tests/Makefile.sources
+++ b/tests/Makefile.sources
@@ -104,6 +104,9 @@ TESTS_progs = \
        vgem_slow \
        $(NULL)
 
+TESTS_progs += sysfs_heartbeat_interval
+sysfs_heartbeat_interval_SOURCES = i915/sysfs_heartbeat_interval.c
+
 TESTS_progs += sysfs_preempt_timeout
 sysfs_preempt_timeout_SOURCES = i915/sysfs_preempt_timeout.c
 
diff --git a/tests/i915/sysfs_heartbeat_interval.c 
b/tests/i915/sysfs_heartbeat_interval.c
new file mode 100644
index 000000000..0ba19b263
--- /dev/null
+++ b/tests/i915/sysfs_heartbeat_interval.c
@@ -0,0 +1,446 @@
+/*
+ * Copyright © 2019 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <signal.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "drmtest.h" /* gem_quiescent_gpu()! */
+#include "i915/gem_engine_topology.h"
+#include "igt_dummyload.h"
+#include "igt_sysfs.h"
+#include "ioctl_wrappers.h" /* igt_require_gem()! */
+#include "sw_sync.h"
+
+#include "igt_debugfs.h"
+
+#define ATTR "heartbeat_interval_ms"
+#define RESET_TIMEOUT 20 /* milliseconds, at least one jiffie for kworker */
+
+static bool __enable_hangcheck(int dir, bool state)
+{
+       return igt_sysfs_set(dir, "enable_hangcheck", state ? "1" : "0");
+}
+
+static void enable_hangcheck(int i915, bool state)
+{
+       int dir;
+
+       dir = igt_sysfs_open_parameters(i915);
+       if (dir < 0) /* no parameters, must be default! */
+               return;
+
+       __enable_hangcheck(dir, state);
+       close(dir);
+}
+
+static void set_heartbeat(int engine, unsigned int value)
+{
+       unsigned int delay = ~value;
+
+       igt_debug("set %s:%d\n", ATTR, value);
+       igt_require(igt_sysfs_printf(engine, ATTR, "%u", value) > 0);
+       igt_sysfs_scanf(engine, ATTR, "%u", &delay);
+       igt_assert_eq(delay, value);
+}
+
+static void test_idempotent(int i915, int engine)
+{
+       unsigned int delays[] = { 1, 1000, 5000, 50000, 123456789 };
+       unsigned int saved;
+
+       /* Quick test that the property reports the values we set */
+
+       igt_assert(igt_sysfs_scanf(engine, ATTR, "%u", &saved) == 1);
+       igt_debug("Initial %s:%u\n", ATTR, saved);
+
+       for (int i = 0; i < ARRAY_SIZE(delays); i++)
+               set_heartbeat(engine, delays[i]);
+
+       set_heartbeat(engine, saved);
+}
+
+static void test_invalid(int i915, int engine)
+{
+       unsigned int saved, delay;
+
+       /* Quick test that we reject any unrepresentable intervals */
+
+       igt_assert(igt_sysfs_scanf(engine, ATTR, "%u", &saved) == 1);
+       igt_debug("Initial %s:%u\n", ATTR, saved);
+
+       igt_sysfs_printf(engine, ATTR, PRIu64, -1);
+       igt_sysfs_scanf(engine, ATTR, "%u", &delay);
+       igt_assert_eq(delay, saved);
+
+       igt_sysfs_printf(engine, ATTR, PRIu64, 10ull << 32);
+       igt_sysfs_scanf(engine, ATTR, "%u", &delay);
+       igt_assert_eq(delay, saved);
+}
+
+static void set_unbannable(int i915, uint32_t ctx)
+{
+       struct drm_i915_gem_context_param p = {
+               .ctx_id = ctx,
+               .param = I915_CONTEXT_PARAM_BANNABLE,
+       };
+
+       gem_context_set_param(i915, &p);
+}
+
+static uint32_t create_context(int i915, unsigned int class, unsigned int 
inst, int prio)
+{
+       uint32_t ctx;
+
+       ctx = gem_context_create_for_engine(i915, class, inst);
+       set_unbannable(i915, ctx);
+       gem_context_set_priority(i915, ctx, prio);
+
+       return ctx;
+}
+
+static uint64_t __test_timeout(int i915, int engine, unsigned int timeout)
+{
+       unsigned int class, inst;
+       struct timespec ts = {};
+       igt_spin_t *spin[2];
+       uint64_t elapsed;
+       uint32_t ctx[2];
+
+       igt_assert(igt_sysfs_scanf(engine, "class", "%u", &class) == 1);
+       igt_assert(igt_sysfs_scanf(engine, "instance", "%u", &inst) == 1);
+
+       set_heartbeat(engine, timeout);
+
+       ctx[0] = create_context(i915, class, inst, 1023);
+       spin[0] = igt_spin_new(i915, ctx[0],
+                              .flags = (IGT_SPIN_NO_PREEMPTION |
+                                        IGT_SPIN_POLL_RUN |
+                                        IGT_SPIN_FENCE_OUT));
+       igt_spin_busywait_until_started(spin[0]);
+
+       ctx[1] = create_context(i915, class, inst, -1023);
+       igt_nsec_elapsed(&ts);
+       spin[1] = igt_spin_new(i915, ctx[1], .flags = IGT_SPIN_POLL_RUN);
+       igt_spin_busywait_until_started(spin[1]);
+       elapsed = igt_nsec_elapsed(&ts);
+
+       igt_spin_free(i915, spin[1]);
+
+       igt_assert_eq(sync_fence_wait(spin[0]->out_fence, RESET_TIMEOUT), 0);
+       igt_assert_eq(sync_fence_status(spin[0]->out_fence), -EIO);
+
+       igt_spin_free(i915, spin[0]);
+
+       gem_context_destroy(i915, ctx[1]);
+       gem_context_destroy(i915, ctx[0]);
+       gem_quiescent_gpu(i915);
+
+       return elapsed;
+}
+
+static void test_precise(int i915, int engine)
+{
+       int delays[] = { 1, 50, 100, 500 };
+       unsigned int saved;
+
+       /*
+        * The heartbeat interval defines how long the kernel waits between
+        * checking on the status of the engines. It first sends down a
+        * heartbeat pulse, waits the interval and sees if the system managed
+        * to complete the pulse. If not, it gives a priority bump to the pulse
+        * and waits again. This is repeated until the priority cannot be bumped
+        * any more, and the system is declared hung.
+        *
+        * If we combine the preemptive pulse with forced preemption, we instead
+        * get a much faster hang detection. Thus in combination we can measure
+        * the system response time to reseting a hog as a measure of the
+        * heartbeat interval, and so confirm it matches our specification.
+        */
+
+       igt_require(igt_sysfs_printf(engine, "preempt_timeout_ms", "%u", 1) == 
1);
+
+       igt_assert(igt_sysfs_scanf(engine, ATTR, "%u", &saved) == 1);
+       igt_debug("Initial %s:%u\n", ATTR, saved);
+       gem_quiescent_gpu(i915);
+
+       for (int i = 0; i < ARRAY_SIZE(delays); i++) {
+               uint64_t elapsed;
+
+               elapsed = __test_timeout(i915, engine, delays[i]);
+               igt_info("%s:%d, elapsed=%.3fms[%d]\n", ATTR,
+                        delays[i], elapsed * 1e-6,
+                        (int)(elapsed / 1000 / 1000));
+
+               /*
+                * It takes a couple of missed heartbeats before we start
+                * terminating hogs, and a little bit of jiffie slack for
+                * scheduling at each step. 150ms should cover all of our
+                * sins and be useful tolerance.
+                */
+               igt_assert_f(elapsed / 1000 / 1000 < 3 * delays[i] + 150,
+                            "Heartbeat interval (and CPR) exceeded 
request!\n");
+       }
+
+       gem_quiescent_gpu(i915);
+       set_heartbeat(engine, saved);
+}
+
+static void test_nopreempt(int i915, int engine)
+{
+       int delays[] = { 1, 50, 100, 500 };
+       unsigned int saved;
+
+       /*
+        * The same principle as test_precise(), except that forced preemption
+        * is disabled (or simply not supported by the platform). This time,
+        * it waits until the system misses a few heartbeat before doing a
+        * per-engine/full-gpu reset. As such it is less precise, but we
+        * can still estimate an upper bound for our specified heartbeat
+        * interval and verify the system conforms.
+        */
+
+       /* Test heartbeats with forced preemption  disabled */
+       igt_sysfs_printf(engine, "preempt_timeout_ms", "%u", 0);
+
+       igt_assert(igt_sysfs_scanf(engine, ATTR, "%u", &saved) == 1);
+       igt_debug("Initial %s:%u\n", ATTR, saved);
+       gem_quiescent_gpu(i915);
+
+       for (int i = 0; i < ARRAY_SIZE(delays); i++) {
+               uint64_t elapsed;
+
+               elapsed = __test_timeout(i915, engine, delays[i]);
+               igt_info("%s:%d, elapsed=%.3fms[%d]\n", ATTR,
+                        delays[i], elapsed * 1e-6,
+                        (int)(elapsed / 1000 / 1000));
+
+               /*
+                * It takes a few missed heartbeats before we start
+                * terminating hogs, and a little bit of jiffie slack for
+                * scheduling at each step. 250ms should cover all of our
+                * sins and be useful tolerance.
+                */
+               igt_assert_f(elapsed / 1000 / 1000 < 5 * delays[i] + 250,
+                            "Heartbeat interval (and CPR) exceeded 
request!\n");
+       }
+
+       gem_quiescent_gpu(i915);
+       set_heartbeat(engine, saved);
+}
+
+static void client(int i915, int engine, int *ctl, int duration, int expect)
+{
+       unsigned int class, inst;
+       unsigned long count = 0;
+       uint32_t ctx;
+
+       igt_assert(igt_sysfs_scanf(engine, "class", "%u", &class) == 1);
+       igt_assert(igt_sysfs_scanf(engine, "instance", "%u", &inst) == 1);
+
+       ctx = create_context(i915, class, inst, 0);
+
+       while (!READ_ONCE(*ctl)) {
+               igt_spin_t *spin;
+
+               spin = igt_spin_new(i915, ctx,
+                                   .flags = (IGT_SPIN_NO_PREEMPTION |
+                                             IGT_SPIN_POLL_RUN |
+                                             IGT_SPIN_FENCE_OUT));
+               igt_spin_busywait_until_started(spin);
+
+               igt_spin_set_timeout(spin, (uint64_t)duration * 1000 * 1000);
+               sync_fence_wait(spin->out_fence, -1);
+
+               igt_assert_eq(sync_fence_status(spin->out_fence), expect);
+               count++;
+       }
+
+       gem_context_destroy(i915, ctx);
+       igt_info("%s client completed %lu spins\n",
+                expect < 0 ? "Bad" : "Good", count);
+}
+
+static void __test_mixed(int i915, int engine,
+                        int heartbeat,
+                        int good,
+                        int bad,
+                        int duration)
+{
+       unsigned int saved;
+       int *shared;
+
+       /*
+        * Given two clients of which one is a hog, be sure we cleanly
+        * terminate the hog leaving the good client to run.
+        */
+
+       igt_assert(igt_sysfs_scanf(engine, ATTR, "%u", &saved) == 1);
+       igt_debug("Initial %s:%u\n", ATTR, saved);
+       gem_quiescent_gpu(i915);
+
+       shared = mmap(NULL, 4096, PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
+       igt_assert(shared != MAP_FAILED);
+
+       set_heartbeat(engine, heartbeat);
+
+       igt_fork(child, 1) /* good client */
+               client(i915, engine, shared, good, 1);
+       igt_fork(child, 1) /* bad client */
+               client(i915, engine, shared, bad, -EIO);
+
+       sleep(duration);
+
+       *shared = true;
+       igt_waitchildren();
+       munmap(shared, 4096);
+
+       gem_quiescent_gpu(i915);
+       set_heartbeat(engine, saved);
+}
+
+static void test_mixed(int i915, int engine)
+{
+       /*
+        * Hogs rarely run alone. Our hang detection must carefully wean
+        * out the hogs from the innocent clients. Thus we run a mixed workload
+        * with non-preemptable hogs that exceed the heartbeat, and quicker
+        * innocents. We inspect the fence status of each to verify that
+        * only the hogs are reset.
+        */
+       igt_require(igt_sysfs_printf(engine, "preempt_timeout_ms", "%u", 1) == 
1);
+       __test_mixed(i915, engine, 10, 10, 100, 5);
+}
+
+static void test_long(int i915, int engine)
+{
+       /*
+        * Some clients relish being hogs, and demand that the system
+        * never do hangchecking. Never is hard to test, so instead we
+        * run over a day and verify that only the super hogs are reset.
+        */
+       igt_sysfs_printf(engine, "preempt_timeout_ms", "%u", 0);
+       __test_mixed(i915, engine,
+                    60 * 1000, /* 60s */
+                    60 * 1000, /* 60s */
+                    300 * 1000, /* 5min */
+                    24 * 3600 /* 24hours */);
+}
+
+static void test_off(int i915, int engine)
+{
+       unsigned int class, inst;
+       unsigned int saved;
+       igt_spin_t *spin;
+       uint32_t ctx;
+
+       /*
+        * Some other clients request that there is never any interruption
+        * or jitter in their workload and so demand that the kernel never
+        * sends a heartbeat to steal precious cycles from their workload.
+        * Turn off the heartbeat and check that the workload is uninterrupted
+        * for 150s.
+        */
+
+       igt_assert(igt_sysfs_scanf(engine, ATTR, "%u", &saved) == 1);
+       igt_debug("Initial %s:%u\n", ATTR, saved);
+       gem_quiescent_gpu(i915);
+
+       igt_assert(igt_sysfs_scanf(engine, "class", "%u", &class) == 1);
+       igt_assert(igt_sysfs_scanf(engine, "instance", "%u", &inst) == 1);
+
+       set_heartbeat(engine, 0);
+
+       ctx = create_context(i915, class, inst, 0);
+
+       spin = igt_spin_new(i915, ctx,
+                           .flags = (IGT_SPIN_POLL_RUN |
+                                     IGT_SPIN_NO_PREEMPTION |
+                                     IGT_SPIN_FENCE_OUT));
+       igt_spin_busywait_until_started(spin);
+
+       for (int i = 0; i < 150; i++) {
+               igt_assert_eq(sync_fence_status(spin->out_fence), 0);
+               sleep(1);
+       }
+
+       set_heartbeat(engine, 1);
+
+       igt_assert_eq(sync_fence_wait(spin->out_fence, 250), 0);
+       igt_assert_eq(sync_fence_status(spin->out_fence), -EIO);
+
+       igt_spin_free(i915, spin);
+
+       gem_quiescent_gpu(i915);
+       set_heartbeat(engine, saved);
+}
+
+igt_main
+{
+       static const struct {
+               const char *name;
+               void (*fn)(int, int);
+       } tests[] = {
+               { "idempotent", test_idempotent },
+               { "invalid", test_invalid },
+               { "precise", test_precise },
+               { "nopreempt", test_nopreempt },
+               { "mixed", test_mixed },
+               { "off", test_off },
+               { "long", test_long },
+               { }
+       };
+       int i915 = -1, engines = -1;
+
+       igt_fixture {
+               int sys;
+
+               i915 = drm_open_driver(DRIVER_INTEL);
+               igt_require_gem(i915);
+               igt_allow_hang(i915, 0, 0);
+
+               sys = igt_sysfs_open(i915);
+               igt_require(sys != -1);
+
+               engines = openat(sys, "engine", O_RDONLY);
+               igt_require(engines != -1);
+               close(sys);
+
+               enable_hangcheck(i915, true);
+       }
+
+       for (typeof(*tests) *t = tests; t->name; t++)
+               igt_subtest_with_dynamic(t->name)
+                       dyn_sysfs_engines(i915, engines, ATTR, t->fn);
+
+       igt_fixture {
+               close(engines);
+               close(i915);
+       }
+}
diff --git a/tests/intel-ci/blacklist.txt b/tests/intel-ci/blacklist.txt
index 1b5442278..a02ef67e6 100644
--- a/tests/intel-ci/blacklist.txt
+++ b/tests/intel-ci/blacklist.txt
@@ -60,6 +60,7 @@ igt@gem_sync@(?!.*basic).*
 igt@gem_tiled_swapping@(?!non-threaded).*
 igt@gem_userptr_blits@(major|minor|forked|mlocked|swapping).*
 igt@gem_wait@.*hang.*
+igt@sysfs_heartbeat_timeout@long.*
 igt@sysfs_preemption_timeout@off.*
 ###############################################
 # GEM: Not worth fixing
diff --git a/tests/meson.build b/tests/meson.build
index bafd00513..3e5952101 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -227,6 +227,7 @@ i915_progs = [
        'i915_query',
        'i915_selftest',
        'i915_suspend',
+       'sysfs_heartbeat_interval',
        'sysfs_preempt_timeout',
 ]
 
-- 
2.25.1

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