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If we pipeline the PTE updates and then do the copy of those pages within a single unpreemptible command packet, we can submit the copies and leave them to be scheduled without having to synchronously wait under a global lock. In order to manage migration, we need to preallocate the page tables (and keep them pinned and available for use at any time), causing a bottleneck for migrations as all clients must contend on the limited resources. By inlining the ppGTT updates and performing the blit atomically, each client only owns the PTE while in use, and so we can reschedule individual operations however we see fit. And most importantly, we do not need to take a global lock on the shared vm, and wait until the operation is complete before releasing the lock for others to claim the PTE for themselves. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Co-developed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> Reviewed-by: Matthew Auld <matthew.auld@intel.com> Signed-off-by: Matthew Auld <matthew.auld@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210617063018.92802-8-thomas.hellstrom@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.