4f88f8747f
The major drawback of commit7e34f4e4aa("drm/i915/gen8+: Add RC6 CTX corruption WA") is that it disables RC6 while Skylake (and friends) is active, and we do not consider the GPU idle until all outstanding requests have been retired and the engine switched over to the kernel context. If userspace is idle, this task falls onto our background idle worker, which only runs roughly once a second, meaning that userspace has to have been idle for a couple of seconds before we enable RC6 again. Naturally, this causes us to consume considerably more energy than before as powersaving is effectively disabled while a display server (here's looking at you Xorg) is running. As execlists will get a completion event as each context is completed, we can use this interrupt to queue a retire worker bound to this engine to cleanup idle timelines. We will then immediately notice the idle engine (without userspace intervention or the aid of the background retire worker) and start parking the GPU. Thus during light workloads, we will do much more work to idle the GPU faster... Hopefully with commensurate power saving! v2: Watch context completions and only look at those local to the engine when retiring to reduce the amount of excess work we perform. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 References:7e34f4e4aa("drm/i915/gen8+: Add RC6 CTX corruption WA") References:2248a28384("drm/i915/gen8+: Add RC6 CTX corruption WA") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris@chris-wilson.co.uk
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.