mainlining shenanigans
e9af4ea2b9
Watching a light workload on Baytrail (running glxgears and a 1080p decode), instead of the system remaining at low frequency, the glxgears would regularly trigger waitboosting after which it would have to spend a few seconds throttling back down. In this case, the waitboosting is counter productive as the minimal wait for glxgears doesn't prevent it from functioning correctly and delivering frames on time. In this case, glxgears happens to almost always be waiting on the current request, which we already expect to complete quickly (see i915_spin_request) and so avoiding the waitboost on the active request and spinning instead provides the best latency without overcommitting to upclocking. However, if the system falls behind we still force the waitboost. Similarly, we will also trigger upclocking if we detect the system is not delivering frames on time - again using a mechanism that tries to detect a miss and not preemptively upclock. v2: Also skip boosting for after missed vblank if the desired request is already active. 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: Radoslaw Szwichtenberg <radoslaw.szwichtenberg@intel.com> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180118131609.16574-1-chris@chris-wilson.co.uk |
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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.