On Thu, Nov 30, 2017 at 09:45:25AM +0000, Chris Wilson wrote: > Quoting Tvrtko Ursulin (2017-11-30 09:18:20) > > 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. > > > > v4: > > * Power domain should be inner to device runtime pm. (Chris) > > * Simplify NEEDS_CSR_GT_PERF_WA macro. (Chris) > > * Handle async DMC loading by moving the GT_IRQ power domain logic into > > intel_runtime_pm. (Daniel, Chris) > > * Include small core GEN9 as well. (Imre) > > > > v5 > > * Special handling for async DMC load is not needed since on failure the > > power domain reference is kept permanently taken. (Imre) > > > > 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> (v2) > > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Cc: Dmitry Rogozhkin <dmitry.v.rogozhkin@xxxxxxxxx> > > --- > > drivers/gpu/drm/i915/i915_drv.h | 4 ++++ > > drivers/gpu/drm/i915/i915_gem.c | 3 +++ > > drivers/gpu/drm/i915/i915_gem_request.c | 14 ++++++++++++++ > > drivers/gpu/drm/i915/intel_runtime_pm.c | 14 ++++++++++++++ > > 4 files changed, 35 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > > index bddd65839f60..59cf11dd5d3b 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 +3286,9 @@ 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) && IS_GEN9(dev_priv) && !IS_SKYLAKE(dev_priv)) Nitpick: could be just !IS_SKYLAKE(), but works in the above way too. For all other platforms the GT_IRQ domain won't be mapped making display_power_get/put on those just a domain ref inc/dec, otherwise a nop. > > + > > #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..c6067cba1dca 100644 > > --- a/drivers/gpu/drm/i915/i915_gem.c > > +++ b/drivers/gpu/drm/i915/i915_gem.c > > @@ -3381,6 +3381,9 @@ i915_gem_idle_work_handler(struct work_struct *work) > > > > if (INTEL_GEN(dev_priv) >= 6) > > gen6_rps_idle(dev_priv); > > + > > + intel_display_power_put(dev_priv, POWER_DOMAIN_GT_IRQ); > > + > > intel_runtime_pm_put(dev_priv); > > out_unlock: > > mutex_unlock(&dev_priv->drm.struct_mutex); > > diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c > > index a90bdd26571f..c28a4ceb016d 100644 > > --- a/drivers/gpu/drm/i915/i915_gem_request.c > > +++ b/drivers/gpu/drm/i915/i915_gem_request.c > > @@ -252,6 +252,20 @@ static void mark_busy(struct drm_i915_private *i915) > > GEM_BUG_ON(!i915->gt.active_requests); > > > > intel_runtime_pm_get_noresume(i915); > > + > > + /* > > + * 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 has negative impact on the performance of the chip with > > + * huge latencies observed in the interrupt handler and elsewhere. > > + * > > + * Work around it by grabbing a GT IRQ power domain whilst there is any > > + * GT activity, preventing any DC state transitions. > > + */ > > + intel_display_power_get(i915, POWER_DOMAIN_GT_IRQ); > > + > > i915->gt.awake = true; > > > > intel_enable_gt_powersave(i915); > > diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c > > index 8315499452dc..48ad0828ace7 100644 > > --- a/drivers/gpu/drm/i915/intel_runtime_pm.c > > +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c > > @@ -130,6 +130,8 @@ intel_display_power_domain_str(enum intel_display_power_domain domain) > > return "INIT"; > > case POWER_DOMAIN_MODESET: > > return "MODESET"; > > + case POWER_DOMAIN_GT_IRQ: > > + return "GT_IRQ"; > > default: > > MISSING_CASE(domain); > > return "?"; > > @@ -1471,6 +1473,9 @@ void intel_display_power_get(struct drm_i915_private *dev_priv, > > { > > struct i915_power_domains *power_domains = &dev_priv->power_domains; > > > > + if (domain == POWER_DOMAIN_GT_IRQ && !NEEDS_CSR_GT_PERF_WA(dev_priv)) > > + return; > > I was hoping that in the magic of the powerdomains, this would just > evaporate (or at least find its own place within the powerwell enabling). Yep, that would be "normally" the case. But since we have only a single set of domains->powerwells mapping for all GEN9_BC we can't isolate SKL that way w/o duplicating the mapping for SKL. Although all GEN9_BC are the same from power well handling POV for some reason there are still separate DMC firmwares for KBL/CFL and SKL. The corruption problem is only fixed in the KBL/CFL firmware the SKL one still to be added to linux-firmware.git .. At that point we can also remove these checks. > > If Imre is happy with plonking this here, > Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Or at least good enough for now and can be improved upon? Yes, looks ok and can adjust for SKL later. > -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
