diff --git a/Documentation/scheduler/sched-ext.rst b/Documentation/scheduler/sched-ext.rst index 497eeaa5ecbe..a707d2181a77 100644 --- a/Documentation/scheduler/sched-ext.rst +++ b/Documentation/scheduler/sched-ext.rst @@ -48,13 +48,16 @@ sched_ext is used only when the BPF scheduler is loaded and running. If a task explicitly sets its scheduling policy to ``SCHED_EXT``, it will be treated as ``SCHED_NORMAL`` and scheduled by CFS until the BPF scheduler is -loaded. On load, such tasks will be switched to and scheduled by sched_ext. +loaded. -The BPF scheduler can choose to schedule all normal and lower class tasks by -calling ``scx_bpf_switch_all()`` from its ``init()`` operation. In this -case, all ``SCHED_NORMAL``, ``SCHED_BATCH``, ``SCHED_IDLE`` and -``SCHED_EXT`` tasks are scheduled by sched_ext. In the example schedulers, -this mode can be selected with the ``-a`` option. +When the BPF scheduler is loaded and ``SCX_OPS_SWITCH_PARTIAL`` is not set +in ``ops->flags``, all ``SCHED_NORMAL``, ``SCHED_BATCH``, ``SCHED_IDLE``, and +``SCHED_EXT`` tasks are scheduled by sched_ext. + +However, when the BPF scheduler is loaded and ``SCX_OPS_SWITCH_PARTIAL`` is +set in ``ops->flags``, only tasks with the ``SCHED_EXT`` policy are scheduled +by sched_ext, while tasks with ``SCHED_NORMAL``, ``SCHED_BATCH`` and +``SCHED_IDLE`` policies are scheduled by CFS. Terminating the sched_ext scheduler program, triggering :kbd:`SysRq-S`, or detection of any internal error including stalled runnable tasks aborts the @@ -109,7 +112,7 @@ Userspace can implement an arbitrary BPF scheduler by loading a set of BPF programs that implement ``struct sched_ext_ops``. The only mandatory field is ``ops.name`` which must be a valid BPF object name. All operations are optional. The following modified excerpt is from -``tools/sched/scx_simple.bpf.c`` showing a minimal global FIFO scheduler. +``tools/sched_ext/scx_simple.bpf.c`` showing a minimal global FIFO scheduler. .. code-block:: c @@ -156,13 +159,12 @@ optional. The following modified excerpt is from scx_bpf_dispatch(p, SCX_DSQ_GLOBAL, SCX_SLICE_DFL, enq_flags); } - s32 BPF_STRUCT_OPS(simple_init) + s32 BPF_STRUCT_OPS_SLEEPABLE(simple_init) { /* - * All SCHED_OTHER, SCHED_IDLE, and SCHED_BATCH tasks should - * use sched_ext. + * By default, all SCHED_EXT, SCHED_OTHER, SCHED_IDLE, and + * SCHED_BATCH tasks should use sched_ext. */ - scx_bpf_switch_all(); return 0; }