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Check that request has not been signaled before acquiring a reference to the request for signaling later in the interrupt handler. The loading of the cacheline (for request->fence.flags) should be "free" when followed by the locked increment of the request->fence.refcount (which then sets the cacheline to exclusive mode), i.e. the cost of test_bit prior to an atomic_inc should be negligible. This should benefit us when we have a pile of bare breadcrumbs (interrupted execbuf) where we may get interrupts faster than we can get rid of the intel_wait, or if the device is too slow to run the bottom-half between interrupts. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170315210726.12095-5-chris@chris-wilson.co.uk
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.