54fc577d90
Since d0aa694b9239 ("drm/i915/pmu: Always sample an active ringbuffer")
the cost of sampling the engine state on execlists platforms became a
little bit higher when both engine busyness and one of the wait states are
being monitored. (Previously the busyness sampling on legacy platforms was
done via seqno comparison so there was no cost of mmio read.)
We can avoid that by skipping busyness sampling when engine supports
software busy stats and so avoid the cost of potential mmio read and
sample accumulation.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190911160730.22687-1-tvrtko.ursulin@linux.intel.com
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.