From 78796877c37cb2c3898c4bcd2a12238d83858287 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 27 Jun 2018 21:13:03 +0100 Subject: [PATCH] drm/i915: Move the irq_counter inside the spinlock Rather than have multiple locked instructions inside the notify_ring() irq handler, move them inside the spinlock and reduce their intrinsic locking. Signed-off-by: Chris Wilson Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20180627201304.15817-3-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_irq.c | 4 ++-- drivers/gpu/drm/i915/i915_request.c | 4 ++-- drivers/gpu/drm/i915/intel_breadcrumbs.c | 11 +++++++---- drivers/gpu/drm/i915/intel_ringbuffer.h | 2 +- 4 files changed, 12 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 4f137ee..c81b4c1 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -1162,8 +1162,6 @@ static void notify_ring(struct intel_engine_cs *engine) if (unlikely(!engine->breadcrumbs.irq_armed)) return; - atomic_inc(&engine->irq_count); - rcu_read_lock(); spin_lock(&engine->breadcrumbs.irq_lock); @@ -1198,6 +1196,8 @@ static void notify_ring(struct intel_engine_cs *engine) tsk = wait->tsk; } } + + engine->breadcrumbs.irq_count++; } else { if (engine->breadcrumbs.irq_armed) __intel_engine_disarm_breadcrumbs(engine); diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index e1dbb54..39b29687 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -1196,7 +1196,7 @@ static bool __i915_spin_request(const struct i915_request *rq, * takes to sleep on a request, on the order of a microsecond. */ - irq = atomic_read(&engine->irq_count); + irq = READ_ONCE(engine->breadcrumbs.irq_count); timeout_us += local_clock_us(&cpu); do { if (i915_seqno_passed(intel_engine_get_seqno(engine), seqno)) @@ -1208,7 +1208,7 @@ static bool __i915_spin_request(const struct i915_request *rq, * assume we won't see one in the near future but require * the engine->seqno_barrier() to fixup coherency. */ - if (atomic_read(&engine->irq_count) != irq) + if (READ_ONCE(engine->breadcrumbs.irq_count) != irq) break; if (signal_pending_state(state, current)) diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c index 86a987b..1db6ba7 100644 --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c @@ -98,12 +98,14 @@ static void intel_breadcrumbs_hangcheck(struct timer_list *t) struct intel_engine_cs *engine = from_timer(engine, t, breadcrumbs.hangcheck); struct intel_breadcrumbs *b = &engine->breadcrumbs; + unsigned int irq_count; if (!b->irq_armed) return; - if (b->hangcheck_interrupts != atomic_read(&engine->irq_count)) { - b->hangcheck_interrupts = atomic_read(&engine->irq_count); + irq_count = READ_ONCE(b->irq_count); + if (b->hangcheck_interrupts != irq_count) { + b->hangcheck_interrupts = irq_count; mod_timer(&b->hangcheck, wait_timeout()); return; } @@ -272,13 +274,14 @@ static bool use_fake_irq(const struct intel_breadcrumbs *b) if (!test_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings)) return false; - /* Only start with the heavy weight fake irq timer if we have not + /* + * Only start with the heavy weight fake irq timer if we have not * seen any interrupts since enabling it the first time. If the * interrupts are still arriving, it means we made a mistake in our * engine->seqno_barrier(), a timing error that should be transient * and unlikely to reoccur. */ - return atomic_read(&engine->irq_count) == b->hangcheck_interrupts; + return READ_ONCE(b->irq_count) == b->hangcheck_interrupts; } static void enable_fake_irq(struct intel_breadcrumbs *b) diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h index a0bc7a8..44ac90e 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.h +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h @@ -345,7 +345,6 @@ struct intel_engine_cs { struct drm_i915_gem_object *default_state; void *pinned_default_state; - atomic_t irq_count; unsigned long irq_posted; #define ENGINE_IRQ_BREADCRUMB 0 #define ENGINE_IRQ_EXECLIST 1 @@ -380,6 +379,7 @@ struct intel_engine_cs { unsigned int hangcheck_interrupts; unsigned int irq_enabled; + unsigned int irq_count; bool irq_armed : 1; I915_SELFTEST_DECLARE(bool mock : 1); -- 2.7.4