On Thu, Dec 12, 2019 at 02:04:57PM +0000, Chris Wilson wrote: > After initialising a preemption request, we give the current resident a > small amount of time to vacate the GPU. The preemption request is for a > higher priority context and should be immediate to maintain high > quality of service (and avoid priority inversion). However, the > preemption granularity of the GPU can be quite coarse and so we need a > compromise. > > The preempt timeout can be adjusted per-engine using, > > /sys/class/drm/card?/engine/*/preempt_timeout_ms > > and can be disabled by setting it to 0. > > Signed-off-by: Chris Wilson <[email protected]>
Code looks good. Tested with other sysfs related patches in the series. The preempt_timeout_ms file exists and can be modified. Tested when there is no reset engine and the sysfs file is not created. Reviewed-by: Steve Carbonari <[email protected]> Tested-by: Steve Carbonari <[email protected] > --- > drivers/gpu/drm/i915/Kconfig.profile | 3 ++ > drivers/gpu/drm/i915/gt/intel_engine_sysfs.c | 48 ++++++++++++++++++++ > drivers/gpu/drm/i915/gt/intel_lrc.c | 2 +- > 3 files changed, 52 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/Kconfig.profile > b/drivers/gpu/drm/i915/Kconfig.profile > index 5f4ec3aec1d2..1f4e98a8532f 100644 > --- a/drivers/gpu/drm/i915/Kconfig.profile > +++ b/drivers/gpu/drm/i915/Kconfig.profile > @@ -33,6 +33,9 @@ config DRM_I915_PREEMPT_TIMEOUT > expires, the HW will be reset to allow the more important context > to execute. > > + This is adjustable via > + /sys/class/drm/card?/engine/*/preempt_timeout_ms > + > May be 0 to disable the timeout. > > config DRM_I915_MAX_REQUEST_BUSYWAIT > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c > b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c > index 2b65fed76435..d299c66cf7ec 100644 > --- a/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c > +++ b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c > @@ -271,6 +271,50 @@ stop_show(struct kobject *kobj, struct kobj_attribute > *attr, char *buf) > static struct kobj_attribute stop_timeout_attr = > __ATTR(stop_timeout_ms, 0644, stop_show, stop_store); > > +static ssize_t > +preempt_timeout_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 timeout; > + int err; > + > + /* > + * After initialising a preemption request, we give the current > + * resident a small amount of time to vacate the GPU. The preemption > + * request is for a higher priority context and should be immediate to > + * maintain high quality of service (and avoid priority inversion). > + * However, the preemption granularity of the GPU can be quite coarse > + * and so we need a compromise. > + */ > + > + err = kstrtoull(buf, 0, &timeout); > + if (err) > + return err; > + > + if (timeout > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT)) > + return -EINVAL; > + > + WRITE_ONCE(engine->props.preempt_timeout_ms, timeout); > + > + if (READ_ONCE(engine->execlists.pending[0])) > + set_timer_ms(&engine->execlists.preempt, timeout); > + > + return count; > +} > + > +static ssize_t > +preempt_timeout_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.preempt_timeout_ms); > +} > + > +static struct kobj_attribute preempt_timeout_attr = > +__ATTR(preempt_timeout_ms, 0644, preempt_timeout_show, > preempt_timeout_store); > + > static void kobj_engine_release(struct kobject *kobj) > { > kfree(kobj); > @@ -341,6 +385,10 @@ void intel_engines_add_sysfs(struct drm_i915_private > *i915) > sysfs_create_file(kobj, ×lice_duration_attr.attr)) > goto err_engine; > > + if (intel_engine_has_preempt_reset(engine) && > + sysfs_create_file(kobj, &preempt_timeout_attr.attr)) > + goto err_engine; > + > if (0) { > err_object: > kobject_put(kobj); > diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c > b/drivers/gpu/drm/i915/gt/intel_lrc.c > index 024a639da787..9a9b23e3d0a3 100644 > --- a/drivers/gpu/drm/i915/gt/intel_lrc.c > +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c > @@ -2252,7 +2252,7 @@ static noinline void preempt_reset(struct > intel_engine_cs *engine) > const unsigned int bit = I915_RESET_ENGINE + engine->id; > unsigned long *lock = &engine->gt->reset.flags; > > - if (i915_modparams.reset < 3) > + if (!intel_has_reset_engine(engine->gt)) > return; > > if (test_and_set_bit(bit, lock)) _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
