When we allow ourselves to sleep before a GPU reset after disabling
submission, even for a few milliseconds, gives an innocent context the
opportunity to clear the GPU before the reset occurs. However, how long
to sleep depends on the typical non-preemptible duration (a similar
problem to determining the ideal preempt-reset timeout or even the
heartbeat interval). As this seems of a hard policy decision, punt it to
userspace.
The timeout can be adjusted using
/sys/class/drm/card?/engine/*/stop_timeout_ms
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Jon Bloomfield <jon.bloomfield@xxxxxxxxx>
---
drivers/gpu/drm/i915/Kconfig.profile | 3 ++
drivers/gpu/drm/i915/gt/intel_engine_sysfs.c | 40 ++++++++++++++++++++
2 files changed, 43 insertions(+)
diff --git a/drivers/gpu/drm/i915/Kconfig.profile b/drivers/gpu/drm/i915/Kconfig.profile
index 9ee3b59685b9..5f4ec3aec1d2 100644
--- a/drivers/gpu/drm/i915/Kconfig.profile
+++ b/drivers/gpu/drm/i915/Kconfig.profile
@@ -63,6 +63,9 @@ config DRM_I915_STOP_TIMEOUT
that the reset itself may take longer and so be more disruptive to
interactive or low latency workloads.
+ This is adjustable via
+ /sys/class/drm/card?/engine/*/stop_timeout_ms
+
config DRM_I915_TIMESLICE_DURATION
int "Scheduling quantum for userspace batches (ms, jiffy granularity)"
default 1 # milliseconds
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c
index 6d87529c64a7..2b65fed76435 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c
@@ -232,6 +232,45 @@ timeslice_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
static struct kobj_attribute timeslice_duration_attr =
__ATTR(timeslice_duration_ms, 0644, timeslice_show, timeslice_store);
+static ssize_t
+stop_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct intel_engine_cs *engine = kobj_to_engine(kobj);
+ unsigned long long duration;
+ int err;
+
+ /*
+ * When we allow ourselves to sleep before a GPU reset after disabling
+ * submission, even for a few milliseconds, gives an innocent context
+ * the opportunity to clear the GPU before the reset occurs. However,
+ * how long to sleep depends on the typical non-preemptible duration
+ * (a similar problem to determining the ideal preempt-reset timeout
+ * or even the heartbeat interval).
+ */
+
+ err = kstrtoull(buf, 0, &duration);
+ if (err)
+ return err;
+
+ if (duration > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
+ return -EINVAL;
+
+ WRITE_ONCE(engine->props.stop_timeout_ms, duration);
+ return count;
+}
+
+static ssize_t
+stop_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+ struct intel_engine_cs *engine = kobj_to_engine(kobj);
+
+ return sprintf(buf, "%lu\n", engine->props.stop_timeout_ms);
+}
+
+static struct kobj_attribute stop_timeout_attr =
+__ATTR(stop_timeout_ms, 0644, stop_show, stop_store);
+
static void kobj_engine_release(struct kobject *kobj)
{
kfree(kobj);
@@ -273,6 +312,7 @@ void intel_engines_add_sysfs(struct drm_i915_private *i915)
&caps_attr.attr,
&all_caps_attr.attr,
&max_spin_attr.attr,
+ &stop_timeout_attr.attr,
NULL
};
--
2.24.0
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