5d36acb719
Invalidate TLB in batches, in order to reduce performance regressions. Currently, every caller performs a full barrier around a TLB invalidation, ignoring all other invalidations that may have already removed their PTEs from the cache. As this is a synchronous operation and can be quite slow, we cause multiple threads to contend on the TLB invalidate mutex blocking userspace. We only need to invalidate the TLB once after replacing our PTE to ensure that there is no possible continued access to the physical address before releasing our pages. By tracking a seqno for each full TLB invalidate we can quickly determine if one has been performed since rewriting the PTE, and only if necessary trigger one for ourselves. That helps to reduce the performance regression introduced by TLB invalidate logic. [mchehab: rebased to not require moving the code to a separate file] Cc: stable@vger.kernel.org Fixes: 7938d61591d3 ("drm/i915: Flush TLBs before releasing backing store") Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Signed-off-by: Chris Wilson <chris.p.wilson@intel.com> Cc: Fei Yang <fei.yang@intel.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org> Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/4e97ef5deb6739cadaaf40aa45620547e9c4ec06.1658924372.git.mchehab@kernel.org
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.