8bb69cbc32
commit 5207c393d3e7dda9aff813d6b3e2264370d241be upstream.
The caching mode for buffer objects with VRAM as a possible
placement was forced to write-combined, regardless of placement.
However, write-combined system memory is expensive to allocate and
even though it is pooled, the pool is expensive to shrink, since
it involves global CPU TLB flushes.
Moreover write-combined system memory from TTM is only reliably
available on x86 and DGFX doesn't have an x86 restriction.
So regardless of the cpu caching mode selected for a bo,
internally use write-back caching mode for system memory on DGFX.
Coherency is maintained, but user-space clients may perceive a
difference in cpu access speeds.
v2:
- Update RB- and Ack tags.
- Rephrase wording in xe_drm.h (Matt Roper)
v3:
- Really rephrase wording.
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Fixes: 622f709ca629 ("drm/xe/uapi: Add support for CPU caching mode")
Cc: Pallavi Mishra <pallavi.mishra@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Effie Yu <effie.yu@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Jose Souza <jose.souza@intel.com>
Cc: Michal Mrozek <michal.mrozek@intel.com>
Cc: <stable@vger.kernel.org> # v6.8+
Acked-by: Matthew Auld <matthew.auld@intel.com>
Acked-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Fixes: 622f709ca629 ("drm/xe/uapi: Add support for CPU caching mode")
Acked-by: Michal Mrozek <michal.mrozek@intel.com>
Acked-by: Effie Yu <effie.yu@intel.com> #On chat
Link: https://patchwork.freedesktop.org/patch/msgid/20240705132828.27714-1-thomas.hellstrom@linux.intel.com
(cherry picked from commit 01e0cfc994be484ddcb9e121e353e51d8bb837c0)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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 reStructuredText 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.