From e23005604b2f815720b00c2b36c9597fd43923cf Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Sat, 1 Aug 2020 17:02:25 +0100 Subject: [PATCH] drm/i915/gt: Hold context/request reference while breadcrumbs are active Currently we hold no actual reference to the request nor context while they are attached to a breadcrumb. To avoid freeing the request/context too early, we serialise with cancel-breadcrumbs by taking the irq spinlock in i915_request_retire(). The alternative is to take a reference for a new breadcrumb and release it upon signaling; removing the more frequently hit contention point in i915_request_retire(). Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20200801160225.6814-2-chris@chris-wilson.co.uk Signed-off-by: Rodrigo Vivi [Joonas: Rebased and reordered into drm-intel-gt-next branch] Signed-off-by: Joonas Lahtinen --- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 103 +++++++++++++++++++--------- drivers/gpu/drm/i915/i915_request.c | 9 ++- 2 files changed, 74 insertions(+), 38 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c index 9dd9996..d8b206e 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -29,6 +29,7 @@ #include "i915_drv.h" #include "i915_trace.h" #include "intel_breadcrumbs.h" +#include "intel_context.h" #include "intel_gt_pm.h" #include "intel_gt_requests.h" @@ -99,6 +100,22 @@ static void __intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b) intel_gt_pm_put_async(b->irq_engine->gt); } +static void add_signaling_context(struct intel_breadcrumbs *b, + struct intel_context *ce) +{ + intel_context_get(ce); + list_add_tail(&ce->signal_link, &b->signalers); + if (list_is_first(&ce->signal_link, &b->signalers)) + __intel_breadcrumbs_arm_irq(b); +} + +static void remove_signaling_context(struct intel_breadcrumbs *b, + struct intel_context *ce) +{ + list_del(&ce->signal_link); + intel_context_put(ce); +} + static inline bool __request_completed(const struct i915_request *rq) { return i915_seqno_passed(__hwsp_seqno(rq), rq->fence.seqno); @@ -107,6 +124,9 @@ static inline bool __request_completed(const struct i915_request *rq) __maybe_unused static bool check_signal_order(struct intel_context *ce, struct i915_request *rq) { + if (rq->context != ce) + return false; + if (!list_is_last(&rq->signal_link, &ce->signals) && i915_seqno_passed(rq->fence.seqno, list_next_entry(rq, signal_link)->fence.seqno)) @@ -158,10 +178,11 @@ static bool __signal_request(struct i915_request *rq, struct list_head *signals) { clear_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags); - if (!__dma_fence_signal(&rq->fence)) + if (!__dma_fence_signal(&rq->fence)) { + i915_request_put(rq); return false; + } - i915_request_get(rq); list_add_tail(&rq->signal_link, signals); return true; } @@ -209,8 +230,8 @@ static void signal_irq_work(struct irq_work *work) /* Advance the list to the first incomplete request */ __list_del_many(&ce->signals, pos); if (&ce->signals == pos) { /* now empty */ - list_del_init(&ce->signal_link); add_retire(b, ce->timeline); + remove_signaling_context(b, ce); } } } @@ -279,6 +300,9 @@ void intel_breadcrumbs_park(struct intel_breadcrumbs *b) spin_lock_irqsave(&b->irq_lock, flags); __intel_breadcrumbs_disarm_irq(b); spin_unlock_irqrestore(&b->irq_lock, flags); + + if (!list_empty(&b->signalers)) + irq_work_queue(&b->irq_work); } void intel_breadcrumbs_free(struct intel_breadcrumbs *b) @@ -295,6 +319,8 @@ static void insert_breadcrumb(struct i915_request *rq, if (test_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags)) return; + i915_request_get(rq); + /* * If the request is already completed, we can transfer it * straight onto a signaled list, and queue the irq worker for @@ -306,32 +332,33 @@ static void insert_breadcrumb(struct i915_request *rq, return; } - __intel_breadcrumbs_arm_irq(b); - - /* - * We keep the seqno in retirement order, so we can break - * inside intel_engine_signal_breadcrumbs as soon as we've - * passed the last completed request (or seen a request that - * hasn't event started). We could walk the timeline->requests, - * but keeping a separate signalers_list has the advantage of - * hopefully being much smaller than the full list and so - * provides faster iteration and detection when there are no - * more interrupts required for this context. - * - * We typically expect to add new signalers in order, so we - * start looking for our insertion point from the tail of - * the list. - */ - list_for_each_prev(pos, &ce->signals) { - struct i915_request *it = - list_entry(pos, typeof(*it), signal_link); + if (list_empty(&ce->signals)) { + add_signaling_context(b, ce); + pos = &ce->signals; + } else { + /* + * We keep the seqno in retirement order, so we can break + * inside intel_engine_signal_breadcrumbs as soon as we've + * passed the last completed request (or seen a request that + * hasn't event started). We could walk the timeline->requests, + * but keeping a separate signalers_list has the advantage of + * hopefully being much smaller than the full list and so + * provides faster iteration and detection when there are no + * more interrupts required for this context. + * + * We typically expect to add new signalers in order, so we + * start looking for our insertion point from the tail of + * the list. + */ + list_for_each_prev(pos, &ce->signals) { + struct i915_request *it = + list_entry(pos, typeof(*it), signal_link); - if (i915_seqno_passed(rq->fence.seqno, it->fence.seqno)) - break; + if (i915_seqno_passed(rq->fence.seqno, it->fence.seqno)) + break; + } } list_add(&rq->signal_link, pos); - if (pos == &ce->signals) /* catch transitions from empty list */ - list_move_tail(&ce->signal_link, &b->signalers); GEM_BUG_ON(!check_signal_order(ce, rq)); set_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags); @@ -412,23 +439,19 @@ void i915_request_cancel_breadcrumb(struct i915_request *rq) list_del(&rq->signal_link); if (list_empty(&ce->signals)) - list_del_init(&ce->signal_link); + remove_signaling_context(b, ce); clear_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags); + i915_request_put(rq); } spin_unlock(&b->irq_lock); } -void intel_engine_print_breadcrumbs(struct intel_engine_cs *engine, - struct drm_printer *p) +static void print_signals(struct intel_breadcrumbs *b, struct drm_printer *p) { - struct intel_breadcrumbs *b = engine->breadcrumbs; struct intel_context *ce; struct i915_request *rq; - if (!b || list_empty(&b->signalers)) - return; - drm_printf(p, "Signals:\n"); spin_lock_irq(&b->irq_lock); @@ -444,3 +467,17 @@ void intel_engine_print_breadcrumbs(struct intel_engine_cs *engine, } spin_unlock_irq(&b->irq_lock); } + +void intel_engine_print_breadcrumbs(struct intel_engine_cs *engine, + struct drm_printer *p) +{ + struct intel_breadcrumbs *b; + + b = engine->breadcrumbs; + if (!b) + return; + + drm_printf(p, "IRQ: %s\n", enableddisabled(b->irq_armed)); + if (!list_empty(&b->signalers)) + print_signals(b, p); +} diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index fcb00b2..20ba3d9 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -296,13 +296,12 @@ bool i915_request_retire(struct i915_request *rq) */ remove_from_engine(rq); - spin_lock_irq(&rq->lock); i915_request_mark_complete(rq); - if (!i915_request_signaled(rq)) + if (!i915_request_signaled(rq)) { + spin_lock_irq(&rq->lock); dma_fence_signal_locked(&rq->fence); - if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &rq->fence.flags)) - i915_request_cancel_breadcrumb(rq); - spin_unlock_irq(&rq->lock); + spin_unlock_irq(&rq->lock); + } if (i915_request_has_waitboost(rq)) { GEM_BUG_ON(!atomic_read(&rq->engine->gt->rps.num_waiters)); -- 2.7.4