Commit 9465f44d authored by Andrea Righi's avatar Andrea Righi Committed by Tejun Heo
Browse files

sched_ext: Documentation: Clarify time slice handling in task lifecycle 



It is not always obvious how a task's time slice can be refilled, either
explicitly from ops.dispatch() or automatically by the sched_ext core,
to skip subsequent ops.enqueue() and ops.dispatch() calls. This
typically happens when the task is the only one running on a CPU.

To make this behavior easier to understand, update the task lifecycle
diagram to explicitly document how time slice handling works in such
cases.

Signed-off-by: default avatarAndrea Righi <arighi@nvidia.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 086ed90a

Documentation/scheduler/sched-ext.rst

+8 −3
Original line number Diff line number Diff line
@@ -313,16 +313,21 @@ by a sched_ext scheduler: 
        ops.runnable();         /* Task becomes ready to run */



        while (task is runnable) {

            if (task is not in a DSQ) {

            if (task is not in a DSQ && task->scx.slice == 0) {

                ops.enqueue();  /* Task can be added to a DSQ */



                /* A CPU becomes available */

                /* Any usable CPU becomes available */



                ops.dispatch(); /* Task is moved to a local DSQ */

            }

            ops.running();      /* Task starts running on its assigned CPU */

            while (task->scx.slice > 0 && task is runnable)

                ops.tick();     /* Called every 1/HZ seconds */

            ops.stopping();     /* Task stops running (time slice expires or wait) */



            /* Task's CPU becomes available */



            ops.dispatch();     /* task->scx.slice can be refilled */

        }



        ops.quiescent();        /* Task releases its assigned CPU (wait) */