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Commit 7c9e934e authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Emit dma-fence (and execlists submit) first from signaler 



When introduced, I thought that reducing client latency from the
signaler was the priority. Since its inception the signaler has become
responsible for keeping the execlists full, via the dma-fence. As this
is very important to minimise overall execution time, signal the
dma-fence first and then signal any waiting clients.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170124110009.28947-8-chris@chris-wilson.co.uk
parent 48ea2554

drivers/gpu/drm/i915/intel_breadcrumbs.c

+4 −4
Original line number Diff line number Diff line
@@ -459,16 +459,16 @@ static int intel_breadcrumbs_signaler(void *arg) 
		 */

		request = READ_ONCE(b->first_signal);

		if (signal_complete(request)) {

			local_bh_disable();

			dma_fence_signal(&request->fence);

			local_bh_enable(); /* kick start the tasklets */



			/* Wake up all other completed waiters and select the

			 * next bottom-half for the next user interrupt.

			 */

			intel_engine_remove_wait(engine,

						 &request->signaling.wait);



			local_bh_disable();

			dma_fence_signal(&request->fence);

			local_bh_enable(); /* kick start the tasklets */



			/* Find the next oldest signal. Note that as we have

			 * not been holding the lock, another client may

			 * have installed an even older signal than the one