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Chris Wilson authored
Originally we would enable and disable the breadcrumb interrupt immediately on demand. This was slow enough to have a large impact (>30%) on tasks that hopped between engines. However, by using a shadow to keep the irq alive for an extra interrupt (see commit 67b807a8 ("drm/i915: Delay disabling the user interrupt for breadcrumbs")) and by recently reducing the cost in adding ourselves to the signal tree, we no longer need to spin-request during await_request to avoid delays in throughput tests. Without the earlier patches to stop the wakeup when signaling if the irq was already active, we saw no improvement in execbuf overhead (and corresponding contention in other clients) despite the removal of the spinner in a simple test like glxgears. This means there will be scenarios where now we spend longer enabling the interrupt than we would have spent spinning, but these are not likely to have as noticeable an impact as the high frequency test cases (where there should not be any regression). Ulterior motive: generalising the engine->sync_to to handle different types of semaphores and non-semaphores. Signed-off-by:
Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Oscar Mateo <oscar.mateo@intel.com> Reviewed-by:
Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by:
Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170608111405.16466-4-chris@chris-wilson.co.uk
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