Riana Tauro 6978c5f5a6 drm/xe/xe_pmu: Add PMU support for engine activity
PMU provides two counters (engine-active-ticks, engine-total-ticks)
to calculate engine activity. When querying engine activity,
user must group these 2 counters using the perf_event
group mechanism to ensure both counters are sampled together.

To list the events

	./perf list
	  xe_0000_03_00.0/engine-active-ticks/	[Kernel PMU event]
	  xe_0000_03_00.0/engine-total-ticks/	[Kernel PMU event]

The formats to be used with the above are

	engine_instance	- config:12-19
	engine_class	- config:20-27
	gt		- config:60-63

The events can then be read using perf tool

./perf stat -e xe_0000_03_00.0/engine-active-ticks,gt=0,
			       engine_class=0,engine_instance=0/,
	       xe_0000_03_00.0/engine-total-ticks,gt=0,
			       engine_class=0,engine_instance=0/ -I 1000

Engine activity can then be calculated as below
engine activity % = (engine active ticks/engine total ticks) * 100

v2: validate gt
    rename total-ticks to engine-total-ticks
    add helper to get hwe (Umesh)

v3: fix checkpatch warning
    add details to documentation (Umesh)
    remove ascii formats from documentation (Lucas)

v4: remove unnecessary warn within raw_spinlock (Lucas)

Signed-off-by: Riana Tauro <riana.tauro@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250224053903.2253539-5-riana.tauro@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
2025-02-24 13:23:57 -08:00
2025-01-23 14:42:21 +01:00
2025-01-23 14:42:21 +01:00
2025-01-23 14:42:21 +01:00
2025-01-23 14:42:21 +01:00
2025-01-23 14:42:21 +01:00
2025-01-19 15:51:45 -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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