d445aaaac0
If the engine is continually completing nops, we can saturate the signaler and keep it working indefinitely. This angers the NMI watchdog! A good example is to disable semaphores on snb and run igt/gem_exec_nop - the parallel, multi-engine workloads are more than sufficient to hog the CPU, preventing the system from even processing ICMP echo replies. v2: Tvrtko dug into cond_resched() on x86 and found that it only depended upon preempt_count and not tif_need_resched() - which means that we would always call schedule() at that point. Fixes:c81d46138d("drm/i915: Convert trace-irq to the breadcrumb waiter") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170404120531.10737-1-chris@chris-wilson.co.uk Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> (cherry picked from commita7980a640c) Signed-off-by: Jani Nikula <jani.nikula@intel.com>