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drm/i915/gt: Expose reset stop timeout via sysfs

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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@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Reviewed-by: Steve Carbonari <steven.carbonari@intel.com>
Tested-by: Steve Carbonari <steven.carbonari@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228131716.3243616-5-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2020-02-28 13:17:14 +00:00
parent 062444bbc6
commit 72338a1f5e
2 changed files with 43 additions and 0 deletions
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3
drivers/gpu/drm/i915/Kconfig.profile
View File

@ -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

40
drivers/gpu/drm/i915/gt/sysfs_engines.c
View File

@ -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
};