Fork of alistair23 Linux kernel for reMarkable from https://github.com/alistair23/linux
3365e2268b
When userspace is passing around swapbuffers using DRI, we frequently have to open and close the same object in the foreign address space. This shows itself as the same object being rebound at roughly 30fps (with a second object also being rebound at 30fps), which involves us having to rewrite the page tables and maintain the drm_mm range manager every time. However, since the object still exists and it is only the local handle that disappears, if we are lazy and do not unbind the VMA immediately when the local user closes the object but defer it until the GPU is idle, then we can reuse the same VMA binding. We still have to be careful to mark the handle and lookup tables as closed to maintain the uABI, just allowing the underlying VMA to be resurrected if the user is able to access the same object from the same context again. If the object itself is destroyed (neither userspace keeping a handle to it), the VMA will be reaped immediately as usual. In the future, this will be even more useful as instantiating a new VMA for use on the GPU will become heavier. A nuisance indeed, so nip it in the bud. v2: s/__i915_vma_final_close/i915_vma_destroy/ etc. v3: Leave a hint as to why we deferred the unbind on close. 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/20180503195115.22309-1-chris@chris-wilson.co.uk |
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| README | ||
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.
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.