[Intel-gfx] [PATCH 2/3] drm/i915/gt: create workqueue dedicated to wake references
Coelho, Luciano
luciano.coelho at intel.com
Fri May 12 09:54:23 UTC 2023
On Fri, 2023-05-12 at 10:32 +0100, Tvrtko Ursulin wrote:
> On 12/05/2023 10:10, Coelho, Luciano wrote:
> > On Fri, 2023-05-12 at 10:04 +0100, Tvrtko Ursulin wrote:
> > > On 11/05/2023 09:20, Luca Coelho wrote:
> > > > Add a work queue in the intel_wakeref structure to be used exclusively
> > > > by the wake reference mechanism. This is needed in order to avoid
> > > > using the system workqueue and relying on flush_scheduled_work().
> > > >
> > > > Cc: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
> > > > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > > > Cc: Jani Nikula <jani.nikula at intel.com>
> > > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > > Signed-off-by: Luca Coelho <luciano.coelho at intel.com>
> > > > ---
> > > > drivers/gpu/drm/i915/gt/intel_engine_cs.c | 7 ++++++-
> > > > drivers/gpu/drm/i915/gt/intel_engine_pm.c | 15 ++++++++++++--
> > > > drivers/gpu/drm/i915/gt/intel_engine_pm.h | 3 ++-
> > > > drivers/gpu/drm/i915/gt/mock_engine.c | 8 +++++++-
> > > > drivers/gpu/drm/i915/intel_wakeref.c | 21 ++++++++++++++-----
> > > > drivers/gpu/drm/i915/intel_wakeref.h | 25 +++++++++++++++--------
> > > > 6 files changed, 60 insertions(+), 19 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > > > index 0aff5bb13c53..6505bfa70cd0 100644
> > > > --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > > > +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > > > @@ -1290,7 +1290,11 @@ static int engine_setup_common(struct intel_engine_cs *engine)
> > > > goto err_cmd_parser;
> > > >
> > > > intel_engine_init_execlists(engine);
> > > > - intel_engine_init__pm(engine);
> > > > +
> > > > + err = intel_engine_init__pm(engine);
> > > > + if (err)
> > > > + goto err_cmd_parser;
> > > > +
> > > > intel_engine_init_retire(engine);
> > > >
> > > > /* Use the whole device by default */
> > > > @@ -1525,6 +1529,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine)
> > > > {
> > > > GEM_BUG_ON(!list_empty(&engine->sched_engine->requests));
> > > >
> > > > + intel_engine_destroy__pm(engine);
> > > > i915_sched_engine_put(engine->sched_engine);
> > > > intel_breadcrumbs_put(engine->breadcrumbs);
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> > > > index ee531a5c142c..859b62cf660f 100644
> > > > --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> > > > +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> > > > @@ -294,14 +294,25 @@ static const struct intel_wakeref_ops wf_ops = {
> > > > .put = __engine_park,
> > > > };
> > > >
> > > > -void intel_engine_init__pm(struct intel_engine_cs *engine)
> > > > +int intel_engine_init__pm(struct intel_engine_cs *engine)
> > > > {
> > > > struct intel_runtime_pm *rpm = engine->uncore->rpm;
> > > > + int err;
> > > > +
> > > > + err = intel_wakeref_init(&engine->wakeref, rpm, &wf_ops);
> > > > + if (err)
> > > > + return err;
> > > >
> > > > - intel_wakeref_init(&engine->wakeref, rpm, &wf_ops);
> > > > intel_engine_init_heartbeat(engine);
> > > >
> > > > intel_gsc_idle_msg_enable(engine);
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +void intel_engine_destroy__pm(struct intel_engine_cs *engine)
> > > > +{
> > > > + intel_wakeref_destroy(&engine->wakeref);
> > > > }
> > > >
> > > > /**
> > > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.h b/drivers/gpu/drm/i915/gt/intel_engine_pm.h
> > > > index d68675925b79..e8568f7d10c6 100644
> > > > --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.h
> > > > +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.h
> > > > @@ -104,7 +104,8 @@ intel_engine_create_kernel_request(struct intel_engine_cs *engine)
> > > > return rq;
> > > > }
> > > >
> > > > -void intel_engine_init__pm(struct intel_engine_cs *engine);
> > > > +int intel_engine_init__pm(struct intel_engine_cs *engine);
> > > > +void intel_engine_destroy__pm(struct intel_engine_cs *engine);
> > > >
> > > > void intel_engine_reset_pinned_contexts(struct intel_engine_cs *engine);
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
> > > > index c0637bf799a3..0a3c702c21e2 100644
> > > > --- a/drivers/gpu/drm/i915/gt/mock_engine.c
> > > > +++ b/drivers/gpu/drm/i915/gt/mock_engine.c
> > > > @@ -336,6 +336,7 @@ static void mock_engine_release(struct intel_engine_cs *engine)
> > > > intel_context_put(engine->kernel_context);
> > > >
> > > > intel_engine_fini_retire(engine);
> > > > + intel_engine_destroy__pm(engine);
> > > > }
> > > >
> > > > struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
> > > > @@ -393,6 +394,7 @@ struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
> > > > int mock_engine_init(struct intel_engine_cs *engine)
> > > > {
> > > > struct intel_context *ce;
> > > > + int err;
> > > >
> > > > INIT_LIST_HEAD(&engine->pinned_contexts_list);
> > > >
> > > > @@ -402,7 +404,11 @@ int mock_engine_init(struct intel_engine_cs *engine)
> > > > engine->sched_engine->private_data = engine;
> > > >
> > > > intel_engine_init_execlists(engine);
> > > > - intel_engine_init__pm(engine);
> > > > +
> > > > + err = intel_engine_init__pm(engine);
> > > > + if (err)
> > > > + return err;
> > > > +
> > > > intel_engine_init_retire(engine);
> > > >
> > > > engine->breadcrumbs = intel_breadcrumbs_create(NULL);
> > > > diff --git a/drivers/gpu/drm/i915/intel_wakeref.c b/drivers/gpu/drm/i915/intel_wakeref.c
> > > > index dfd87d082218..6bae609e1312 100644
> > > > --- a/drivers/gpu/drm/i915/intel_wakeref.c
> > > > +++ b/drivers/gpu/drm/i915/intel_wakeref.c
> > > > @@ -74,7 +74,7 @@ void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags)
> > > >
> > > > /* Assume we are not in process context and so cannot sleep. */
> > > > if (flags & INTEL_WAKEREF_PUT_ASYNC || !mutex_trylock(&wf->mutex)) {
> > > > - mod_delayed_work(system_wq, &wf->work,
> > > > + mod_delayed_work(wf->wq, &wf->work,
> > > > FIELD_GET(INTEL_WAKEREF_PUT_DELAY, flags));
> > > > return;
> > > > }
> > > > @@ -93,10 +93,10 @@ static void __intel_wakeref_put_work(struct work_struct *wrk)
> > > > ____intel_wakeref_put_last(wf);
> > > > }
> > > >
> > > > -void __intel_wakeref_init(struct intel_wakeref *wf,
> > > > - struct intel_runtime_pm *rpm,
> > > > - const struct intel_wakeref_ops *ops,
> > > > - struct intel_wakeref_lockclass *key)
> > > > +int __intel_wakeref_init(struct intel_wakeref *wf,
> > > > + struct intel_runtime_pm *rpm,
> > > > + const struct intel_wakeref_ops *ops,
> > > > + struct intel_wakeref_lockclass *key)
> > > > {
> > > > wf->rpm = rpm;
> > > > wf->ops = ops;
> > > > @@ -105,9 +105,20 @@ void __intel_wakeref_init(struct intel_wakeref *wf,
> > > > atomic_set(&wf->count, 0);
> > > > wf->wakeref = 0;
> > > >
> > > > + wf->wq = alloc_workqueue("i1915-wakeref", 0, 0);
> > >
> > > Typo here -
> >
> > Oh, good catch! This is one of my "favorite" typos, for some reason.
>
> Yes, I had the same one. :) Patch 3/3 too.
>
> > > I wanted to ask however - why does this particular wq
> > > "deserves" to be dedicated and can't just use one of the
> > > drm_i915_private ones?
> >
> > It's because there's no easy way to get access to the drm_i915_private
> > structure from here. And I don't think this work needs to be in sync
> > with the rest of the works in i915.
>
> Yeah I don't think it needs to be synchronised either. Was just thinking
> if we really need to be creating a bunch of separate workqueues (one per
> engine) for not much use, or instead could just add a backpointer to
> either intel_wakeref or intel_runtime_pm. Latter already has rpm->kdev
> so could plausably be replaced with rpm->i915.
>
> Actually, looking at intel_runtime_pm_init_early, you could get to i915
> via wf->rpm and container_of.
Yeah, I considered that, but using container_of() can be problematic
when we're not sure where exactly the element is coming from. My worry
was this:
int intel_engine_init__pm(struct intel_engine_cs *engine)
{
struct intel_runtime_pm *rpm = engine->uncore->rpm;
int err;
err = intel_wakeref_init(&engine->wakeref, rpm, &wf_ops);
[...]
}
In this case, we're getting to __intel_wakeref_init() with an *rpm that
is coming from an intel_uncore structure and not from
drm_i915_private...
--
Cheers,
Luca.
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