On 12/2/2024 05:45, Peter Zijlstra wrote:
On Sat, Nov 30, 2024 at 08:06:52AM -0600, Mario Limonciello wrote:
+Thread Classification and Ranking Table Interaction
+----------------------------------------------------
+
+The thread classification is used to select into a ranking table that describes
+an efficiency and performance ranking for each classification.
+
+Threads are classified during runtime into enumerated classes. The classes represent
+thread performance/power characteristics that may benefit from special scheduling behaviors.
+The below table depicts an example of thread classification and a preference where a given thread
+should be scheduled based on its thread class. The real time thread classification is consumed
+by the operating system and is used to inform the scheduler of where the thread should be placed.
+
+Thread Classification Example Table
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
++----------+----------------+-------------------------------+---------------------+---------+
+| class ID | Classification | Preferred scheduling behavior | Preemption priority | Counter |
++----------+----------------+-------------------------------+---------------------+---------+
+| 0 | Default | Performant | Highest | |
++----------+----------------+-------------------------------+---------------------+---------+
+| 1 | Non-scalable | Efficient | Lowest | PMCx1A1 |
++----------+----------------+-------------------------------+---------------------+---------+
+| 2 | I/O bound | Efficient | Lowest | PMCx044 |
++----------+----------------+-------------------------------+---------------------+---------+
+
+Thread classification is performed by the hardware each time that the thread is switched out.
+Threads that don't meet any hardware specified criteria will be classified as "default".
I'm not seeing this part in the patches, am I needing to read more
careful?
Patch 1 is intended to explain how it should/would work, it's not 100%
implemented in the patch series. After the baseline plumbing is landed,
use of thread classification information in the scheduler should be
future development.
