On Thu, Dec 12, 2019 at 02:04:56PM +0000, Chris Wilson wrote:
> 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>
Code looks good.
Tested with other sysfs related patches in the series.
The stop_timeout_ms file exists and can be modified.
Reviewed-by: Steve Carbonari <steven.carbonari@xxxxxxxxx>
Tested-by: Steve Carbonari <steven.carbonari@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
> };
>
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