On Wed, Nov 29, 2017 at 11:10:58AM +0000, Chris Wilson wrote: > Quoting Tvrtko Ursulin (2017-11-29 10:59:27) > > From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > > > > It seems that the DMC likes to transition between the DC states a lot when > > there are no connected displays (no active power domains) during command > > submission. > > > > This activity on DC states has a negative impact on the performance of the > > chip with huge latencies observed in the interrupt handlers and elsewhere. > > Simple tests like igt/gem_latency -n 0 are slowed down by a factor of > > eight. > > > > Work around it by introducing a new power domain named, > > POWER_DOMAIN_GT_IRQ, associtated with the "DC off" power well, which is > > held for the duration of command submission activity. > > > > v2: > > * Add commit text as comment in i915_gem_mark_busy. (Chris Wilson) > > * Protect macro body with braces. (Jani Nikula) > > > > v3: > > * Add dedicated power domain for clarity. (Chris, Imre) > > * Commit message and comment text updates. > > * Apply to all big-core GEN9 parts apart for Skylake which is pending DMC > > firmware release. > > > > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100572 > > Testcase: igt/gem_exec_nop/headless > > Cc: Imre Deak <imre.deak@xxxxxxxxx> > > Acked-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Cc: Dmitry Rogozhkin <dmitry.v.rogozhkin@xxxxxxxxx> > > --- > > drivers/gpu/drm/i915/i915_drv.h | 5 +++++ > > drivers/gpu/drm/i915/i915_gem.c | 4 ++++ > > drivers/gpu/drm/i915/i915_gem_request.c | 14 ++++++++++++++ > > drivers/gpu/drm/i915/intel_runtime_pm.c | 4 ++++ > > 4 files changed, 27 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > > index bddd65839f60..17340aadc566 100644 > > --- a/drivers/gpu/drm/i915/i915_drv.h > > +++ b/drivers/gpu/drm/i915/i915_drv.h > > @@ -398,6 +398,7 @@ enum intel_display_power_domain { > > POWER_DOMAIN_AUX_D, > > POWER_DOMAIN_GMBUS, > > POWER_DOMAIN_MODESET, > > + POWER_DOMAIN_GT_IRQ, > > POWER_DOMAIN_INIT, > > > > POWER_DOMAIN_NUM, > > @@ -3285,6 +3286,10 @@ intel_info(const struct drm_i915_private *dev_priv) > > #define GT_FREQUENCY_MULTIPLIER 50 > > #define GEN9_FREQ_SCALER 3 > > > > +#define NEEDS_CSR_GT_PERF_WA(dev_priv) \ > > + (HAS_CSR(dev_priv) && (dev_priv)->csr.dmc_payload && \ > > We can't have a dmc_payload unless CSR, right? > > > + IS_GEN9_BC(dev_priv) && !IS_SKYLAKE(dev_priv)) > > + > > #include "i915_trace.h" > > > > static inline bool intel_vtd_active(void) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > > index 354b0546a191..feec2a621120 100644 > > --- a/drivers/gpu/drm/i915/i915_gem.c > > +++ b/drivers/gpu/drm/i915/i915_gem.c > > @@ -3381,7 +3381,11 @@ i915_gem_idle_work_handler(struct work_struct *work) > > > > if (INTEL_GEN(dev_priv) >= 6) > > gen6_rps_idle(dev_priv); > > + > > intel_runtime_pm_put(dev_priv); > > + > > + if (NEEDS_CSR_GT_PERF_WA(dev_priv)) > > + intel_display_power_put(dev_priv, POWER_DOMAIN_GT_IRQ); > > Which is the outer wakeref? I expect runtime, being device-global, to be > the outer wakeref, with display_power_put being the inner subset. Yes, logically the runtime ref is the outer one. But intel_display_power_get() takes a runtime ref too and both runtime and display power references can be held for "a long time" and so can be taken in both order. > -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
