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drm/i915: Move the irq_counter inside the spinlock

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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 <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180627201304.15817-3-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2018-06-27 21:13:03 +01:00
parent 69dc4d003e
commit 78796877c3
4 changed files with 12 additions and 9 deletions

4
drivers/gpu/drm/i915/i915_irq.c
View file

@ -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);

4
drivers/gpu/drm/i915/i915_request.c
View file

@ -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))

11
drivers/gpu/drm/i915/intel_breadcrumbs.c
View file

@ -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)

2
drivers/gpu/drm/i915/intel_ringbuffer.h
View file

@ -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);