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: c81d46138da6 ("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 commit a7980a640cbd339aa80f406d1786a275a2c320bc)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.