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Currently, we try to report to the shrinker the precise number of objects (pages) that are available to be reaped at this moment. This requires searching all objects with allocated pages to see if they fulfill the search criteria, and this count is performed quite frequently. (The shrinker tries to free ~128 pages on each invocation, before which we count all the objects; counting takes longer than unbinding the objects!) If we take the pragmatic view that with sufficient desire, all objects are eventually reapable (they become inactive, or no longer used as framebuffer etc), we can simply return the count of pinned pages maintained during get_pages/put_pages rather than walk the lists every time. The downside is that we may (slightly) over-report the number of objects/pages we could shrink and so penalize ourselves by shrinking more than required. This is mitigated by keeping the order in which we shrink objects such that we avoid penalizing active and frequently used objects, and if memory is so tight that we need to free them we would need to anyway. v2: Only expose shrinkable objects to the shrinker; a small reduction in not considering stolen and foreign objects. v3: Restore the tracking from a "backup" copy from before the gem/ split Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Matthew Auld <matthew.auld@intel.com> Reviewed-by: Matthew Auld <matthew.auld@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190530203500.26272-2-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.