Lucas De Marchi 83db047d94 drm/xe: Stop accumulating LRC timestamp on job_free
The exec queue timestamp is only really useful when it's being queried
through the fdinfo. There's no need to update it so often, on every
job_free. Tracing a simple app like vkcube running shows an update
rate of ~ 120Hz. In case of discrete, the BO is on vram, creating a lot
of pcie transactions.

The update on job_free() is used to cover a gap: if exec
queue is created and destroyed rapidly, before a new query, the
timestamp still needs to be accumulated and accounted for in the xef.

Initial implementation in commit 6109f24f87 ("drm/xe: Add helper to
accumulate exec queue runtime") couldn't do it on the exec_queue_fini
since the xef could be gone at that point. However since commit
ce8c161cba ("drm/xe: Add ref counting for xe_file") the xef is
refcounted and the exec queue always holds a reference, making this safe
now.

Improve the fix in commit 2149ded630 ("drm/xe: Fix use after free when
client stats are captured") by reducing the frequency in which the
update is needed.

Fixes: 2149ded630 ("drm/xe: Fix use after free when client stats are captured")
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241104143815.2112272-3-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
2024-11-05 13:38:46 -08:00

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.
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