[5/7] drm/i915: Don't need a timer to wake us up

Commit Message

Tvrtko Ursulin Jan. 11, 2016, 2:08 p.m. UTC

From: Tvrtko Ursulin <[e-mail]>

We can avoid open-coding the schedule wake-up since

   commit 9cff8adeaa34b5d2802f03f89803da57856b3b72
   Author: NeilBrown <[e-mail]>
   Date:   Fri Feb 13 15:49:17 2015 +1100

       sched: Prevent recursion in io_schedule()

exported the io_schedule_timeout function which we can now use
to simplify the code in __i915_wait_request.

v2: New commit message. (Daniel Vetter)

Signed-off-by: Tvrtko Ursulin <[e-mail]>
Cc: Chris Wilson <[e-mail]>
Reviewed-by: Daniel Vetter <[e-mail]>
---
 drivers/gpu/drm/i915/i915_gem.c | 28 ++++++++--------------------
 1 file changed, 8 insertions(+), 20 deletions(-)

Comments

Chris Wilson Jan. 11, 2016, 2:33 p.m. UTC | #1

On Mon, Jan 11, 2016 at 02:08:39PM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <[e-mail]>
> 
> We can avoid open-coding the schedule wake-up since
> 
>    commit 9cff8adeaa34b5d2802f03f89803da57856b3b72
>    Author: NeilBrown <[e-mail]>
>    Date:   Fri Feb 13 15:49:17 2015 +1100
> 
>        sched: Prevent recursion in io_schedule()
> 
> exported the io_schedule_timeout function which we can now use
> to simplify the code in __i915_wait_request.
> 
> v2: New commit message. (Daniel Vetter)
> 
> Signed-off-by: Tvrtko Ursulin <[e-mail]>
> Cc: Chris Wilson <[e-mail]>
> Reviewed-by: Daniel Vetter <[e-mail]>

I don't like this because the timer concept still turns out to be useful
when we separate the timer from the bottom-half. And so we have a patch
to remove it and then we add it back again because it serves a purpose.
-Chris

Tvrtko Ursulin Jan. 12, 2016, 10:20 a.m. UTC | #2

On 11/01/16 14:33, Chris Wilson wrote:
> On Mon, Jan 11, 2016 at 02:08:39PM +0000, Tvrtko Ursulin wrote:
>> From: Tvrtko Ursulin <[e-mail]>
>>
>> We can avoid open-coding the schedule wake-up since
>>
>>     commit 9cff8adeaa34b5d2802f03f89803da57856b3b72
>>     Author: NeilBrown <[e-mail]>
>>     Date:   Fri Feb 13 15:49:17 2015 +1100
>>
>>         sched: Prevent recursion in io_schedule()
>>
>> exported the io_schedule_timeout function which we can now use
>> to simplify the code in __i915_wait_request.
>>
>> v2: New commit message. (Daniel Vetter)
>>
>> Signed-off-by: Tvrtko Ursulin <[e-mail]>
>> Cc: Chris Wilson <[e-mail]>
>> Reviewed-by: Daniel Vetter <[e-mail]>
>
> I don't like this because the timer concept still turns out to be useful
> when we separate the timer from the bottom-half. And so we have a patch
> to remove it and then we add it back again because it serves a purpose.

-EWHATEVER

Regards,

Tvrtko

Patch

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6c60e04fc09c..de98dc41fb9f 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1135,11 +1135,6 @@  i915_gem_check_wedge(struct i915_gpu_error *error,
 	return 0;
 }
 
-static void fake_irq(unsigned long data)
-{
-	wake_up_process((struct task_struct *)data);
-}
-
 static bool missed_irq(struct drm_i915_private *dev_priv,
 		       struct intel_engine_cs *ring)
 {
@@ -1291,7 +1286,7 @@  int __i915_wait_request(struct drm_i915_gem_request *req,
 	}
 
 	for (;;) {
-		struct timer_list timer;
+		long sched_timeout;
 
 		prepare_to_wait(&ring->irq_queue, &wait, state);
 
@@ -1321,21 +1316,14 @@  int __i915_wait_request(struct drm_i915_gem_request *req,
 			break;
 		}
 
-		timer.function = NULL;
-		if (timeout || missed_irq(dev_priv, ring)) {
-			unsigned long expire;
-
-			setup_timer_on_stack(&timer, fake_irq, (unsigned long)current);
-			expire = missed_irq(dev_priv, ring) ? jiffies + 1 : timeout_expire;
-			mod_timer(&timer, expire);
-		}
-
-		io_schedule();
+		if (timeout)
+			sched_timeout = timeout_expire - jiffies;
+		else if (missed_irq(dev_priv, ring))
+			sched_timeout = 1;
+		else
+			sched_timeout = MAX_SCHEDULE_TIMEOUT;
 
-		if (timer.function) {
-			del_singleshot_timer_sync(&timer);
-			destroy_timer_on_stack(&timer);
-		}
+		io_schedule_timeout(sched_timeout);
 	}
 	if (!irq_test_in_progress)
 		ring->irq_put(ring);