| Message ID | 20211004220637.14746-5-matthew.brost@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Parallel submission aka multi-bb execbuf | expand |
On 10/4/2021 15:06, Matthew Brost wrote: > Calling switch_to_kernel_context isn't needed if the engine PM reference > is taken while all user contexts are pinned as if don't have PM ref that > guarantees that all user contexts scheduling is disabled. By not calling > switch_to_kernel_context we save on issuing a request to the engine. > > v2: > (Daniel Vetter) > - Add FIXME comment about pushing switch_to_kernel_context to backend > v3: > (John Harrison) > - Update commit message > - Fix workding comment > > Signed-off-by: Matthew Brost <matthew.brost@intel.com> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: John Harrison <John.C.Harrison@Intel.com> > --- > drivers/gpu/drm/i915/gt/intel_engine_pm.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c > index dacd62773735..a1334b48dde7 100644 > --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c > +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c > @@ -162,6 +162,19 @@ static bool switch_to_kernel_context(struct intel_engine_cs *engine) > unsigned long flags; > bool result = true; > > + /* > + * This is execlist specific behaviour intended to ensure the GPU is > + * idle by switching to a known 'safe' context. With GuC submission, the > + * same idle guarantee is achieved by other means (disabling > + * scheduling). Further, switching to a 'safe' context has no effect > + * with GuC submission as the scheduler can just switch back again. > + * > + * FIXME: Move this backend scheduler specific behaviour into the > + * scheduler backend. > + */ > + if (intel_engine_uses_guc(engine)) > + return true; > + > /* GPU is pointing to the void, as good as in the kernel context. */ > if (intel_gt_is_wedged(engine->gt)) > return true;
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c index dacd62773735..a1334b48dde7 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c @@ -162,6 +162,19 @@ static bool switch_to_kernel_context(struct intel_engine_cs *engine) unsigned long flags; bool result = true; + /* + * This is execlist specific behaviour intended to ensure the GPU is + * idle by switching to a known 'safe' context. With GuC submission, the + * same idle guarantee is achieved by other means (disabling + * scheduling). Further, switching to a 'safe' context has no effect + * with GuC submission as the scheduler can just switch back again. + * + * FIXME: Move this backend scheduler specific behaviour into the + * scheduler backend. + */ + if (intel_engine_uses_guc(engine)) + return true; + /* GPU is pointing to the void, as good as in the kernel context. */ if (intel_gt_is_wedged(engine->gt)) return true;