3d7a64b992
When first enabling preemption, we hesitated from making it a free-for-all
where every higher priority client would force a preempt-to-idle cycle
and take over from all lower priority clients. We hesitated because we
were uncertain just how well preemption would work in practice, whether
the preemption latency itself would detract from the latency gains for
higher priority tasks and whether it would work at all. Since
introducing preemption, we have been enabling it for more common tasks,
even giving normal clients a small preemptive boost when they first
start (to aide fairness and improve interactivity). Now lets take one
step further and give permission for all normal (priority:0) clients to
preempt any idle (priority:<0) task so that users running long compute
jobs do not overly impact other jobs (i.e. their desktop) and the system
remains responsive under such idle loads.
References: f6322eddaff7 ("drm/i915/preemption: Allow preemption between submission ports")
References: b16c765122f9 ("drm/i915: Priority boost for new clients")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: "Bloomfield, Jon" <jon.bloomfield@intel.com>
Cc: "Stead, Alan" <alan.stead@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190204084116.3013-1-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.