From e9eaf82d97a2b05460ff5ef6a3e07446f7d049fe Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 1 Oct 2018 15:47:55 +0100 Subject: [PATCH] drm/i915: Priority boost for waiting clients Latency is in the eye of the beholder. In the case where a client stops and waits for the gpu, give that request chain a small priority boost (not so that it overtakes higher priority clients, to preserve the external ordering) so that ideally the wait completes earlier. v2: Tvrtko recommends to keep the boost-from-user-stall as small as possible and to allow new client flows to be preferred for interactivity over stalls. Testcase: igt/gem_sync/switch-default Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Cc: Joonas Lahtinen Cc: Dmitry Rogozhkin Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20181001144755.7978-3-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem.c | 5 +++- drivers/gpu/drm/i915/i915_request.c | 2 ++ drivers/gpu/drm/i915/i915_request.h | 5 ++-- drivers/gpu/drm/i915/i915_scheduler.c | 34 ++++++++++++++++++++++----- drivers/gpu/drm/i915/i915_scheduler.h | 7 ++++-- 5 files changed, 42 insertions(+), 11 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 28e943ee8b5e..7d45e71100bc 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1748,6 +1748,7 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data, */ err = i915_gem_object_wait(obj, I915_WAIT_INTERRUPTIBLE | + I915_WAIT_PRIORITY | (write_domain ? I915_WAIT_ALL : 0), MAX_SCHEDULE_TIMEOUT, to_rps_client(file)); @@ -3751,7 +3752,9 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file) start = ktime_get(); ret = i915_gem_object_wait(obj, - I915_WAIT_INTERRUPTIBLE | I915_WAIT_ALL, + I915_WAIT_INTERRUPTIBLE | + I915_WAIT_PRIORITY | + I915_WAIT_ALL, to_wait_timeout(args->timeout_ns), to_rps_client(file)); diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index d73ad490a261..abd4dacbab8e 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -1237,6 +1237,8 @@ long i915_request_wait(struct i915_request *rq, add_wait_queue(errq, &reset); intel_wait_init(&wait); + if (flags & I915_WAIT_PRIORITY) + i915_schedule_bump_priority(rq, I915_PRIORITY_WAIT); restart: do { diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 5f7361e0fca6..90e9d170a0cd 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -277,8 +277,9 @@ long i915_request_wait(struct i915_request *rq, __attribute__((nonnull(1))); #define I915_WAIT_INTERRUPTIBLE BIT(0) #define I915_WAIT_LOCKED BIT(1) /* struct_mutex held, handle GPU reset */ -#define I915_WAIT_ALL BIT(2) /* used by i915_gem_object_wait() */ -#define I915_WAIT_FOR_IDLE_BOOST BIT(3) +#define I915_WAIT_PRIORITY BIT(2) /* small priority bump for the request */ +#define I915_WAIT_ALL BIT(3) /* used by i915_gem_object_wait() */ +#define I915_WAIT_FOR_IDLE_BOOST BIT(4) static inline bool intel_engine_has_started(struct intel_engine_cs *engine, u32 seqno); diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c index de9a2ba7c3bc..340faea6c08a 100644 --- a/drivers/gpu/drm/i915/i915_scheduler.c +++ b/drivers/gpu/drm/i915/i915_scheduler.c @@ -239,7 +239,8 @@ sched_lock_engine(struct i915_sched_node *node, struct intel_engine_cs *locked) return engine; } -void i915_schedule(struct i915_request *rq, const struct i915_sched_attr *attr) +static void __i915_schedule(struct i915_request *rq, + const struct i915_sched_attr *attr) { struct list_head *uninitialized_var(pl); struct intel_engine_cs *engine, *last; @@ -248,6 +249,8 @@ void i915_schedule(struct i915_request *rq, const struct i915_sched_attr *attr) const int prio = attr->priority; LIST_HEAD(dfs); + /* Needed in order to use the temporary link inside i915_dependency */ + lockdep_assert_held(&schedule_lock); GEM_BUG_ON(prio == I915_PRIORITY_INVALID); if (i915_request_completed(rq)) @@ -256,9 +259,6 @@ void i915_schedule(struct i915_request *rq, const struct i915_sched_attr *attr) if (prio <= READ_ONCE(rq->sched.attr.priority)) return; - /* Needed in order to use the temporary link inside i915_dependency */ - spin_lock(&schedule_lock); - stack.signaler = &rq->sched; list_add(&stack.dfs_link, &dfs); @@ -312,7 +312,7 @@ void i915_schedule(struct i915_request *rq, const struct i915_sched_attr *attr) rq->sched.attr = *attr; if (stack.dfs_link.next == stack.dfs_link.prev) - goto out_unlock; + return; __list_del_entry(&stack.dfs_link); } @@ -371,7 +371,29 @@ void i915_schedule(struct i915_request *rq, const struct i915_sched_attr *attr) } spin_unlock_irq(&engine->timeline.lock); +} -out_unlock: +void i915_schedule(struct i915_request *rq, const struct i915_sched_attr *attr) +{ + spin_lock(&schedule_lock); + __i915_schedule(rq, attr); spin_unlock(&schedule_lock); } + +void i915_schedule_bump_priority(struct i915_request *rq, unsigned int bump) +{ + struct i915_sched_attr attr; + + GEM_BUG_ON(bump & ~I915_PRIORITY_MASK); + + if (READ_ONCE(rq->sched.attr.priority) == I915_PRIORITY_INVALID) + return; + + spin_lock_bh(&schedule_lock); + + attr = rq->sched.attr; + attr.priority |= bump; + __i915_schedule(rq, &attr); + + spin_unlock_bh(&schedule_lock); +} diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h index 68d84a45ad7f..dbe9cb7ecd82 100644 --- a/drivers/gpu/drm/i915/i915_scheduler.h +++ b/drivers/gpu/drm/i915/i915_scheduler.h @@ -24,13 +24,14 @@ enum { I915_PRIORITY_INVALID = INT_MIN }; -#define I915_USER_PRIORITY_SHIFT 1 +#define I915_USER_PRIORITY_SHIFT 2 #define I915_USER_PRIORITY(x) ((x) << I915_USER_PRIORITY_SHIFT) #define I915_PRIORITY_COUNT BIT(I915_USER_PRIORITY_SHIFT) #define I915_PRIORITY_MASK (I915_PRIORITY_COUNT - 1) -#define I915_PRIORITY_NEWCLIENT ((u8)BIT(0)) +#define I915_PRIORITY_WAIT ((u8)BIT(0)) +#define I915_PRIORITY_NEWCLIENT ((u8)BIT(1)) struct i915_sched_attr { /** @@ -99,6 +100,8 @@ void i915_sched_node_fini(struct drm_i915_private *i915, void i915_schedule(struct i915_request *request, const struct i915_sched_attr *attr); +void i915_schedule_bump_priority(struct i915_request *rq, unsigned int bump); + struct list_head * i915_sched_lookup_priolist(struct intel_engine_cs *engine, int prio); -- 2.30.2