Re: [Intel-gfx] [PATCH 03/14] drm/i915/execlists: Flush the tasklet on parking
Quoting Tvrtko Ursulin (2019-05-02 15:24:16)
>
> On 02/05/2019 15:21, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2019-05-02 15:14:08)
> >>
> >> On 02/05/2019 14:53, Chris Wilson wrote:
> >>> Quoting Tvrtko Ursulin (2019-05-02 14:48:18)
>
> On 01/05/2019 12:45, Chris Wilson wrote:
> > Tidy up the cleanup sequence by always ensure that the tasklet is
> > flushed on parking (before we cleanup). The parking provides a
> > convenient point to ensure that the backend is truly idle.
> >
> > Signed-off-by: Chris Wilson
> > ---
> > drivers/gpu/drm/i915/gt/intel_lrc.c | 7 ++-
> > drivers/gpu/drm/i915/intel_guc_submission.c | 1 +
> > 2 files changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c
> > b/drivers/gpu/drm/i915/gt/intel_lrc.c
> > index 851e62ddcb87..7be54b868d8e 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> > @@ -2331,6 +2331,11 @@ static int gen8_init_rcs_context(struct
> > i915_request *rq)
> > return i915_gem_render_state_emit(rq);
> > }
> >
> > +static void execlists_park(struct intel_engine_cs *engine)
> > +{
> > + tasklet_kill(&engine->execlists.tasklet);
>
> Isn't it actually a problem if tasklet is scheduled and unstarted, or
> even in progress at the point of engine getting parked?
> >>>
> >>> That would be a broken driver. :|
> >>>
> >>> We must be quite sure that engine isn't going to send an interrupt as we
> >>> are just about to drop the wakeref we need to service that interrupt.
> >>>
> >>> tasklet_kill()
> >>> GEM_BUG_ON(engine->execlists.active);
> >>
> >> Or instead of both:
> >>
> >> /* Tasklet must not be running or scheduled at this point. */
> >> GEM_BUG_ON(engine->execlists.tasklet.state);
> >
> > There's the dilemma that we start parking based on retirement not
> > final CS event.
>
> But engine->park() is called once the last engine pm reference is
> dropped. Are we dropping the last reference with a CS event pending?
Potentially we are.
i915_request_retire() -> context->exit() -> engine->park()
At no point along that chain do we actually check we have flushed the
backend. The tasklet_kill() would flush if the interrupt had already
been sent, but that's not very strict.
Oh well, you've talked me into to re-adding the wait loop here.
-Chris
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Re: [Intel-gfx] [PATCH 03/14] drm/i915/execlists: Flush the tasklet on parking
On 02/05/2019 15:21, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2019-05-02 15:14:08)
On 02/05/2019 14:53, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2019-05-02 14:48:18)
On 01/05/2019 12:45, Chris Wilson wrote:
Tidy up the cleanup sequence by always ensure that the tasklet is
flushed on parking (before we cleanup). The parking provides a
convenient point to ensure that the backend is truly idle.
Signed-off-by: Chris Wilson
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 7 ++-
drivers/gpu/drm/i915/intel_guc_submission.c | 1 +
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c
b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 851e62ddcb87..7be54b868d8e 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -2331,6 +2331,11 @@ static int gen8_init_rcs_context(struct i915_request *rq)
return i915_gem_render_state_emit(rq);
}
+static void execlists_park(struct intel_engine_cs *engine)
+{
+ tasklet_kill(&engine->execlists.tasklet);
Isn't it actually a problem if tasklet is scheduled and unstarted, or
even in progress at the point of engine getting parked?
That would be a broken driver. :|
We must be quite sure that engine isn't going to send an interrupt as we
are just about to drop the wakeref we need to service that interrupt.
tasklet_kill()
GEM_BUG_ON(engine->execlists.active);
Or instead of both:
/* Tasklet must not be running or scheduled at this point. */
GEM_BUG_ON(engine->execlists.tasklet.state);
There's the dilemma that we start parking based on retirement not
final CS event.
But engine->park() is called once the last engine pm reference is
dropped. Are we dropping the last reference with a CS event pending?
Regards,
Tvrtko
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Re: [Intel-gfx] [PATCH 03/14] drm/i915/execlists: Flush the tasklet on parking
Quoting Tvrtko Ursulin (2019-05-02 15:14:08)
>
> On 02/05/2019 14:53, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2019-05-02 14:48:18)
> >>
> >> On 01/05/2019 12:45, Chris Wilson wrote:
> >>> Tidy up the cleanup sequence by always ensure that the tasklet is
> >>> flushed on parking (before we cleanup). The parking provides a
> >>> convenient point to ensure that the backend is truly idle.
> >>>
> >>> Signed-off-by: Chris Wilson
> >>> ---
> >>>drivers/gpu/drm/i915/gt/intel_lrc.c | 7 ++-
> >>>drivers/gpu/drm/i915/intel_guc_submission.c | 1 +
> >>>2 files changed, 7 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c
> >>> b/drivers/gpu/drm/i915/gt/intel_lrc.c
> >>> index 851e62ddcb87..7be54b868d8e 100644
> >>> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> >>> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> >>> @@ -2331,6 +2331,11 @@ static int gen8_init_rcs_context(struct
> >>> i915_request *rq)
> >>>return i915_gem_render_state_emit(rq);
> >>>}
> >>>
> >>> +static void execlists_park(struct intel_engine_cs *engine)
> >>> +{
> >>> + tasklet_kill(&engine->execlists.tasklet);
> >>
> >> Isn't it actually a problem if tasklet is scheduled and unstarted, or
> >> even in progress at the point of engine getting parked?
> >
> > That would be a broken driver. :|
> >
> > We must be quite sure that engine isn't going to send an interrupt as we
> > are just about to drop the wakeref we need to service that interrupt.
> >
> > tasklet_kill()
> > GEM_BUG_ON(engine->execlists.active);
>
> Or instead of both:
>
> /* Tasklet must not be running or scheduled at this point. */
> GEM_BUG_ON(engine->execlists.tasklet.state);
There's the dilemma that we start parking based on retirement not
final CS event.
-Chris
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Re: [Intel-gfx] [PATCH 03/14] drm/i915/execlists: Flush the tasklet on parking
On 02/05/2019 14:53, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2019-05-02 14:48:18)
On 01/05/2019 12:45, Chris Wilson wrote:
Tidy up the cleanup sequence by always ensure that the tasklet is
flushed on parking (before we cleanup). The parking provides a
convenient point to ensure that the backend is truly idle.
Signed-off-by: Chris Wilson
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 7 ++-
drivers/gpu/drm/i915/intel_guc_submission.c | 1 +
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c
b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 851e62ddcb87..7be54b868d8e 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -2331,6 +2331,11 @@ static int gen8_init_rcs_context(struct i915_request *rq)
return i915_gem_render_state_emit(rq);
}
+static void execlists_park(struct intel_engine_cs *engine)
+{
+ tasklet_kill(&engine->execlists.tasklet);
Isn't it actually a problem if tasklet is scheduled and unstarted, or
even in progress at the point of engine getting parked?
That would be a broken driver. :|
We must be quite sure that engine isn't going to send an interrupt as we
are just about to drop the wakeref we need to service that interrupt.
tasklet_kill()
GEM_BUG_ON(engine->execlists.active);
Or instead of both:
/* Tasklet must not be running or scheduled at this point. */
GEM_BUG_ON(engine->execlists.tasklet.state);
?
Regards,
Tvrtko
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Re: [Intel-gfx] [PATCH 03/14] drm/i915/execlists: Flush the tasklet on parking
Quoting Tvrtko Ursulin (2019-05-02 14:48:18)
>
> On 01/05/2019 12:45, Chris Wilson wrote:
> > Tidy up the cleanup sequence by always ensure that the tasklet is
> > flushed on parking (before we cleanup). The parking provides a
> > convenient point to ensure that the backend is truly idle.
> >
> > Signed-off-by: Chris Wilson
> > ---
> > drivers/gpu/drm/i915/gt/intel_lrc.c | 7 ++-
> > drivers/gpu/drm/i915/intel_guc_submission.c | 1 +
> > 2 files changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c
> > b/drivers/gpu/drm/i915/gt/intel_lrc.c
> > index 851e62ddcb87..7be54b868d8e 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> > @@ -2331,6 +2331,11 @@ static int gen8_init_rcs_context(struct i915_request
> > *rq)
> > return i915_gem_render_state_emit(rq);
> > }
> >
> > +static void execlists_park(struct intel_engine_cs *engine)
> > +{
> > + tasklet_kill(&engine->execlists.tasklet);
>
> Isn't it actually a problem if tasklet is scheduled and unstarted, or
> even in progress at the point of engine getting parked?
That would be a broken driver. :|
We must be quite sure that engine isn't going to send an interrupt as we
are just about to drop the wakeref we need to service that interrupt.
tasklet_kill()
GEM_BUG_ON(engine->execlists.active);
-Chris
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Re: [Intel-gfx] [PATCH 03/14] drm/i915/execlists: Flush the tasklet on parking
On 01/05/2019 12:45, Chris Wilson wrote:
Tidy up the cleanup sequence by always ensure that the tasklet is
flushed on parking (before we cleanup). The parking provides a
convenient point to ensure that the backend is truly idle.
Signed-off-by: Chris Wilson
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 7 ++-
drivers/gpu/drm/i915/intel_guc_submission.c | 1 +
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c
b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 851e62ddcb87..7be54b868d8e 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -2331,6 +2331,11 @@ static int gen8_init_rcs_context(struct i915_request *rq)
return i915_gem_render_state_emit(rq);
}
+static void execlists_park(struct intel_engine_cs *engine)
+{
+ tasklet_kill(&engine->execlists.tasklet);
Isn't it actually a problem if tasklet is scheduled and unstarted, or
even in progress at the point of engine getting parked?
Regards,
Tvrtko
+}
+
void intel_execlists_set_default_submission(struct intel_engine_cs *engine)
{
engine->submit_request = execlists_submit_request;
@@ -2342,7 +2347,7 @@ void intel_execlists_set_default_submission(struct
intel_engine_cs *engine)
engine->reset.reset = execlists_reset;
engine->reset.finish = execlists_reset_finish;
- engine->park = NULL;
+ engine->park = execlists_park;
engine->unpark = NULL;
engine->flags |= I915_ENGINE_SUPPORTS_STATS;
diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c
b/drivers/gpu/drm/i915/intel_guc_submission.c
index 4c814344809c..ed94001028f2 100644
--- a/drivers/gpu/drm/i915/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/intel_guc_submission.c
@@ -1363,6 +1363,7 @@ static void guc_interrupts_release(struct
drm_i915_private *dev_priv)
static void guc_submission_park(struct intel_engine_cs *engine)
{
+ tasklet_kill(&engine->execlists.tasklet);
intel_engine_unpin_breadcrumbs_irq(engine);
engine->flags &= ~I915_ENGINE_NEEDS_BREADCRUMB_TASKLET;
}
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