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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 <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Dmitry Rogozhkin <dmitry.v.rogozhkin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181001144755.7978-3-chris@chris-wilson.co.uk
hifive-unleashed-5.1
Chris Wilson 2018-10-01 15:47:55 +01:00
parent e2f3496e93
commit e9eaf82d97
5 changed files with 42 additions and 11 deletions
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5
drivers/gpu/drm/i915/i915_gem.c
View File

@ -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));

2
drivers/gpu/drm/i915/i915_request.c
View File

@ -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 {

5
drivers/gpu/drm/i915/i915_request.h
View File

@ -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);

34
drivers/gpu/drm/i915/i915_scheduler.c
View File

@ -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);
}

7
drivers/gpu/drm/i915/i915_scheduler.h
View File

@ -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);