diff --git a/Documentation/scheduler/sched-ext.rst b/Documentation/scheduler/sched-ext.rst index e95b323a693e..f4f7d8f4f9e4 100644 --- a/Documentation/scheduler/sched-ext.rst +++ b/Documentation/scheduler/sched-ext.rst @@ -43,7 +43,6 @@ options should be enabled to use sched_ext: CONFIG_DEBUG_INFO_BTF=y CONFIG_BPF_JIT_ALWAYS_ON=y CONFIG_BPF_JIT_DEFAULT_ON=y - CONFIG_PAHOLE_HAS_BTF_TAG=y sched_ext is used only when the BPF scheduler is loaded and running. @@ -410,6 +409,8 @@ Where to Look The functions prefixed with ``scx_bpf_`` can be called from the BPF scheduler. +* ``kernel/sched/ext_idle.c`` contains the built-in idle CPU selection policy. + * ``tools/sched_ext/`` hosts example BPF scheduler implementations. * ``scx_simple[.bpf].c``: Minimal global FIFO scheduler example using a @@ -418,13 +419,35 @@ Where to Look * ``scx_qmap[.bpf].c``: A multi-level FIFO scheduler supporting five levels of priority implemented with ``BPF_MAP_TYPE_QUEUE``. + * ``scx_central[.bpf].c``: A central FIFO scheduler where all scheduling + decisions are made on one CPU, demonstrating ``LOCAL_ON`` dispatching, + tickless operation, and kthread preemption. + + * ``scx_cpu0[.bpf].c``: A scheduler that queues all tasks to a shared DSQ + and only dispatches them on CPU0 in FIFO order. Useful for testing bypass + behavior. + + * ``scx_flatcg[.bpf].c``: A flattened cgroup hierarchy scheduler + implementing hierarchical weight-based cgroup CPU control by compounding + each cgroup's share at every level into a single flat scheduling layer. + + * ``scx_pair[.bpf].c``: A core-scheduling example that always makes + sibling CPU pairs execute tasks from the same CPU cgroup. + + * ``scx_sdt[.bpf].c``: A variation of ``scx_simple`` demonstrating BPF + arena memory management for per-task data. + + * ``scx_userland[.bpf].c``: A minimal scheduler demonstrating user space + scheduling. Tasks with CPU affinity are direct-dispatched in FIFO order; + all others are scheduled in user space by a simple vruntime scheduler. + ABI Instability =============== The APIs provided by sched_ext to BPF schedulers programs have no stability guarantees. This includes the ops table callbacks and constants defined in ``include/linux/sched/ext.h``, as well as the ``scx_bpf_`` kfuncs defined in -``kernel/sched/ext.c``. +``kernel/sched/ext.c`` and ``kernel/sched/ext_idle.c``. While we will attempt to provide a relatively stable API surface when possible, they are subject to change without warning between kernel diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index e25b3593dd30..72b7a87f66ec 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -1728,16 +1728,15 @@ static void clr_task_runnable(struct task_struct *p, bool reset_runnable_at) p->scx.flags |= SCX_TASK_RESET_RUNNABLE_AT; } -static void enqueue_task_scx(struct rq *rq, struct task_struct *p, int enq_flags) +static void enqueue_task_scx(struct rq *rq, struct task_struct *p, int core_enq_flags) { struct scx_sched *sch = scx_task_sched(p); int sticky_cpu = p->scx.sticky_cpu; + u64 enq_flags = core_enq_flags | rq->scx.extra_enq_flags; if (enq_flags & ENQUEUE_WAKEUP) rq->scx.flags |= SCX_RQ_IN_WAKEUP; - enq_flags |= rq->scx.extra_enq_flags; - /* * Restoring a running task will be immediately followed by * set_next_task_scx() which expects the task to not be on the BPF