From 889230489b6b138ba97ba2f13fc9644a3d16d0d2 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 29 Jan 2018 14:41:04 +0000 Subject: [PATCH] drm/i915: Always run hangcheck while the GPU is busy Previously, we relied on only running the hangcheck while somebody was waiting on the GPU, in order to minimise the amount of time hangcheck had to run. (If nobody was watching the GPU, nobody would notice if the GPU wasn't responding -- eventually somebody would care and so kick hangcheck into action.) However, this falls apart from around commit 4680816be336 ("drm/i915: Wait first for submission, before waiting for request completion"), as not all waiters declare themselves to hangcheck and so we could switch off hangcheck and miss GPU hangs even when waiting under the struct_mutex. If we enable hangcheck from the first request submission, and let it run until the GPU is idle again, we forgo all the complexity involved with only enabling around waiters. We just have to remember to be careful that we do not declare a GPU hang when idly waiting for the next request to be come ready, as we will run hangcheck continuously even when the engines are stalled waiting for external events. This should be true already as we should only be tracking requests submitted to hardware for execution as an indicator that the engine is busy. Fixes: 4680816be336 ("drm/i915: Wait first for submission, before waiting for request completion" Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104840 Signed-off-by: Chris Wilson Cc: Chris Wilson Cc: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20180129144104.3921-1-chris@chris-wilson.co.uk Reviewed-by: Mika Kuoppala --- drivers/gpu/drm/i915/i915_gem.c | 7 +++---- drivers/gpu/drm/i915/i915_gem_request.c | 2 ++ drivers/gpu/drm/i915/intel_breadcrumbs.c | 11 ----------- drivers/gpu/drm/i915/intel_hangcheck.c | 7 +------ 4 files changed, 6 insertions(+), 21 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 062b214..63308ec 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3322,16 +3322,15 @@ i915_gem_retire_work_handler(struct work_struct *work) mutex_unlock(&dev->struct_mutex); } - /* Keep the retire handler running until we are finally idle. + /* + * Keep the retire handler running until we are finally idle. * We do not need to do this test under locking as in the worst-case * we queue the retire worker once too often. */ - if (READ_ONCE(dev_priv->gt.awake)) { - i915_queue_hangcheck(dev_priv); + if (READ_ONCE(dev_priv->gt.awake)) queue_delayed_work(dev_priv->wq, &dev_priv->gt.retire_work, round_jiffies_up_relative(HZ)); - } } static void shrink_caches(struct drm_i915_private *i915) diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c index 0a890ef..cf2f389 100644 --- a/drivers/gpu/drm/i915/i915_gem_request.c +++ b/drivers/gpu/drm/i915/i915_gem_request.c @@ -285,6 +285,8 @@ static void mark_busy(struct drm_i915_private *i915) intel_engines_unpark(i915); + i915_queue_hangcheck(i915); + queue_delayed_work(i915->wq, &i915->gt.retire_work, round_jiffies_up_relative(HZ)); diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c index 86acac0..62b2a20 100644 --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c @@ -149,17 +149,6 @@ static void intel_breadcrumbs_fake_irq(struct timer_list *t) return; mod_timer(&b->fake_irq, jiffies + 1); - - /* Ensure that even if the GPU hangs, we get woken up. - * - * However, note that if no one is waiting, we never notice - * a gpu hang. Eventually, we will have to wait for a resource - * held by the GPU and so trigger a hangcheck. In the most - * pathological case, this will be upon memory starvation! To - * prevent this, we also queue the hangcheck from the retire - * worker. - */ - i915_queue_hangcheck(engine->i915); } static void irq_enable(struct intel_engine_cs *engine) diff --git a/drivers/gpu/drm/i915/intel_hangcheck.c b/drivers/gpu/drm/i915/intel_hangcheck.c index 31f01d6..348a4f7 100644 --- a/drivers/gpu/drm/i915/intel_hangcheck.c +++ b/drivers/gpu/drm/i915/intel_hangcheck.c @@ -411,7 +411,6 @@ static void i915_hangcheck_elapsed(struct work_struct *work) struct intel_engine_cs *engine; enum intel_engine_id id; unsigned int hung = 0, stuck = 0; - int busy_count = 0; if (!i915_modparams.enable_hangcheck) return; @@ -429,7 +428,6 @@ static void i915_hangcheck_elapsed(struct work_struct *work) intel_uncore_arm_unclaimed_mmio_detection(dev_priv); for_each_engine(engine, dev_priv, id) { - const bool busy = intel_engine_has_waiter(engine); struct intel_engine_hangcheck hc; semaphore_clear_deadlocks(dev_priv); @@ -443,16 +441,13 @@ static void i915_hangcheck_elapsed(struct work_struct *work) if (hc.action != ENGINE_DEAD) stuck |= intel_engine_flag(engine); } - - busy_count += busy; } if (hung) hangcheck_declare_hang(dev_priv, hung, stuck); /* Reset timer in case GPU hangs without another request being added */ - if (busy_count) - i915_queue_hangcheck(dev_priv); + i915_queue_hangcheck(dev_priv); } void intel_engine_init_hangcheck(struct intel_engine_cs *engine) -- 2.7.4