[PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

[PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

[Tejun Heo]

Hello,

[v1] -> v2: Comment and documentation updates.

In sched_ext API, a repeatedly reported pain point is the overuse of the
verb "dispatch" and confusion around "consume":

- ops.dispatch()
- scx_bpf_dispatch[_vtime]()
- scx_bpf_consume()
- scx_bpf_dispatch[_vtime]_from_dsq*()

This overloading of the term is historical. Originally, there were only
built-in DSQs and moving a task into a DSQ always dispatched it for
execution. Using the verb "dispatch" for the kfuncs to move tasks into these
DSQs made sense.

Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
from a non-local DSQ to a local DSQ and this operation was named "consume".
This was already confusing as a task could be dispatched to a user DSQ from
ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
user DSQ.

Clean up the API with the following renames:

1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()

This patchset is on top of sched_ext/for-6.13 72b85bf6a7f6 ("sched_ext:
scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context") and
contains the following patches:

 0001-sched_ext-Rename-scx_bpf_dispatch-_vtime-to-scx_bpf_.patch
 0002-sched_ext-Rename-scx_bpf_consume-to-scx_bpf_dsq_move.patch
 0003-sched_ext-Rename-scx_bpf_dispatch-_vtime-_from_dsq-s.patch

and is always available in the following git branch:

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-api-rename-dispatch-v2

diffstat follows. Thanks.

 Documentation/scheduler/sched-ext.rst    |   71 ++++++-------
 kernel/sched/ext.c                       |  243 +++++++++++++++++++++++++++++-----------------
 tools/sched_ext/include/scx/common.bpf.h |   18 +--
 tools/sched_ext/include/scx/compat.bpf.h |  117 +++++++++++++++++++---
 tools/sched_ext/scx_central.bpf.c        |   14 +-
 tools/sched_ext/scx_flatcg.bpf.c         |   20 ++-
 tools/sched_ext/scx_qmap.bpf.c           |   36 +++---
 tools/sched_ext/scx_simple.bpf.c         |   16 +--
 8 files changed, 348 insertions(+), 187 deletions(-)

--
tejun

[v2] http://lkml.kernel.org/r/20241109194853.580310-1-tj@kernel.org

[PATCH 1/3] sched_ext: Rename scx_bpf_dispatch[_vtime]() to scx_bpf_dsq_insert[_vtime]()

[Tejun Heo]

In sched_ext API, a repeatedly reported pain point is the overuse of the
verb "dispatch" and confusion around "consume":

- ops.dispatch()
- scx_bpf_dispatch[_vtime]()
- scx_bpf_consume()
- scx_bpf_dispatch[_vtime]_from_dsq*()

This overloading of the term is historical. Originally, there were only
built-in DSQs and moving a task into a DSQ always dispatched it for
execution. Using the verb "dispatch" for the kfuncs to move tasks into these
DSQs made sense.

Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
from a non-local DSQ to a local DSQ and this operation was named "consume".
This was already confusing as a task could be dispatched to a user DSQ from
ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
user DSQ.

Clean up the API with the following renames:

1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()

This patch performs the first set of renames. Compatibility is maintained
by:

- The previous kfunc names are still provided by the kernel so that old
  binaries can run. Kernel generates a warning when the old names are used.

- compat.bpf.h provides wrappers for the new names which automatically fall
  back to the old names when running on older kernels. They also trigger
  build error if old names are used for new builds.

The compat features will be dropped after v6.15.

v2: Documentation updates.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrea Righi <arighi@nvidia.com>
Cc: Changwoo Min <multics69@gmail.com>
Cc: Johannes Bechberger <me@mostlynerdless.de>
Cc: Giovanni Gherdovich <ggherdovich@suse.com>
Cc: Dan Schatzberg <dschatzberg@meta.com>
Cc: Ming Yang <yougmark94@gmail.com>
---
 Documentation/scheduler/sched-ext.rst    |  50 +++++-----
 kernel/sched/ext.c                       | 111 +++++++++++++----------
 tools/sched_ext/include/scx/common.bpf.h |   4 +-
 tools/sched_ext/include/scx/compat.bpf.h |  26 ++++++
 tools/sched_ext/scx_central.bpf.c        |  10 +-
 tools/sched_ext/scx_flatcg.bpf.c         |  14 +--
 tools/sched_ext/scx_qmap.bpf.c           |  12 +--
 tools/sched_ext/scx_simple.bpf.c         |  14 +--
 8 files changed, 144 insertions(+), 97 deletions(-)

diff --git a/Documentation/scheduler/sched-ext.rst b/Documentation/scheduler/sched-ext.rst
index 7b59bbd2e564..ee4af97701bf 100644
--- a/Documentation/scheduler/sched-ext.rst
+++ b/Documentation/scheduler/sched-ext.rst
@@ -130,7 +130,7 @@ optional. The following modified excerpt is from
      * Decide which CPU a task should be migrated to before being
      * enqueued (either at wakeup, fork time, or exec time). If an
      * idle core is found by the default ops.select_cpu() implementation,
-     * then dispatch the task directly to SCX_DSQ_LOCAL and skip the
+     * then insert the task directly into SCX_DSQ_LOCAL and skip the
      * ops.enqueue() callback.
      *
      * Note that this implementation has exactly the same behavior as the
@@ -148,15 +148,15 @@ optional. The following modified excerpt is from
             cpu = scx_bpf_select_cpu_dfl(p, prev_cpu, wake_flags, &direct);
 
             if (direct)
-                    scx_bpf_dispatch(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, 0);
+                    scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, 0);
 
             return cpu;
     }
 
     /*
-     * Do a direct dispatch of a task to the global DSQ. This ops.enqueue()
-     * callback will only be invoked if we failed to find a core to dispatch
-     * to in ops.select_cpu() above.
+     * Do a direct insertion of a task to the global DSQ. This ops.enqueue()
+     * callback will only be invoked if we failed to find a core to insert
+     * into in ops.select_cpu() above.
      *
      * Note that this implementation has exactly the same behavior as the
      * default ops.enqueue implementation, which just dispatches the task
@@ -166,7 +166,7 @@ optional. The following modified excerpt is from
      */
     void BPF_STRUCT_OPS(simple_enqueue, struct task_struct *p, u64 enq_flags)
     {
-            scx_bpf_dispatch(p, SCX_DSQ_GLOBAL, SCX_SLICE_DFL, enq_flags);
+            scx_bpf_dsq_insert(p, SCX_DSQ_GLOBAL, SCX_SLICE_DFL, enq_flags);
     }
 
     s32 BPF_STRUCT_OPS_SLEEPABLE(simple_init)
@@ -202,7 +202,7 @@ and one local dsq per CPU (``SCX_DSQ_LOCAL``). The BPF scheduler can manage
 an arbitrary number of dsq's using ``scx_bpf_create_dsq()`` and
 ``scx_bpf_destroy_dsq()``.
 
-A CPU always executes a task from its local DSQ. A task is "dispatched" to a
+A CPU always executes a task from its local DSQ. A task is "inserted" into a
 DSQ. A non-local DSQ is "consumed" to transfer a task to the consuming CPU's
 local DSQ.
 
@@ -229,26 +229,26 @@ The following briefly shows how a waking task is scheduled and executed.
    scheduler can wake up any cpu using the ``scx_bpf_kick_cpu()`` helper,
    using ``ops.select_cpu()`` judiciously can be simpler and more efficient.
 
-   A task can be immediately dispatched to a DSQ from ``ops.select_cpu()`` by
-   calling ``scx_bpf_dispatch()``. If the task is dispatched to
-   ``SCX_DSQ_LOCAL`` from ``ops.select_cpu()``, it will be dispatched to the
+   A task can be immediately inserted into a DSQ from ``ops.select_cpu()``
+   by calling ``scx_bpf_dsq_insert()``. If the task is inserted into
+   ``SCX_DSQ_LOCAL`` from ``ops.select_cpu()``, it will be inserted into the
    local DSQ of whichever CPU is returned from ``ops.select_cpu()``.
-   Additionally, dispatching directly from ``ops.select_cpu()`` will cause the
+   Additionally, inserting directly from ``ops.select_cpu()`` will cause the
    ``ops.enqueue()`` callback to be skipped.
 
    Note that the scheduler core will ignore an invalid CPU selection, for
    example, if it's outside the allowed cpumask of the task.
 
 2. Once the target CPU is selected, ``ops.enqueue()`` is invoked (unless the
-   task was dispatched directly from ``ops.select_cpu()``). ``ops.enqueue()``
+   task was inserted directly from ``ops.select_cpu()``). ``ops.enqueue()``
    can make one of the following decisions:
 
-   * Immediately dispatch the task to either the global or local DSQ by
-     calling ``scx_bpf_dispatch()`` with ``SCX_DSQ_GLOBAL`` or
+   * Immediately insert the task into either the global or local DSQ by
+     calling ``scx_bpf_dsq_insert()`` with ``SCX_DSQ_GLOBAL`` or
      ``SCX_DSQ_LOCAL``, respectively.
 
-   * Immediately dispatch the task to a custom DSQ by calling
-     ``scx_bpf_dispatch()`` with a DSQ ID which is smaller than 2^63.
+   * Immediately insert the task into a custom DSQ by calling
+     ``scx_bpf_dsq_insert()`` with a DSQ ID which is smaller than 2^63.
 
    * Queue the task on the BPF side.
 
@@ -257,11 +257,11 @@ The following briefly shows how a waking task is scheduled and executed.
    run, ``ops.dispatch()`` is invoked which can use the following two
    functions to populate the local DSQ.
 
-   * ``scx_bpf_dispatch()`` dispatches a task to a DSQ. Any target DSQ can
-     be used - ``SCX_DSQ_LOCAL``, ``SCX_DSQ_LOCAL_ON | cpu``,
-     ``SCX_DSQ_GLOBAL`` or a custom DSQ. While ``scx_bpf_dispatch()``
+   * ``scx_bpf_dsq_insert()`` inserts a task to a DSQ. Any target DSQ can be
+     used - ``SCX_DSQ_LOCAL``, ``SCX_DSQ_LOCAL_ON | cpu``,
+     ``SCX_DSQ_GLOBAL`` or a custom DSQ. While ``scx_bpf_dsq_insert()``
      currently can't be called with BPF locks held, this is being worked on
-     and will be supported. ``scx_bpf_dispatch()`` schedules dispatching
+     and will be supported. ``scx_bpf_dsq_insert()`` schedules insertion
      rather than performing them immediately. There can be up to
      ``ops.dispatch_max_batch`` pending tasks.
 
@@ -288,12 +288,12 @@ built-in DSQs are used, there is no need to implement ``ops.dispatch()`` as
 a task is never queued on the BPF scheduler and both the local and global
 DSQs are consumed automatically.
 
-``scx_bpf_dispatch()`` queues the task on the FIFO of the target DSQ. Use
-``scx_bpf_dispatch_vtime()`` for the priority queue. Internal DSQs such as
+``scx_bpf_dsq_insert()`` inserts the task on the FIFO of the target DSQ. Use
+``scx_bpf_dsq_insert_vtime()`` for the priority queue. Internal DSQs such as
 ``SCX_DSQ_LOCAL`` and ``SCX_DSQ_GLOBAL`` do not support priority-queue
-dispatching, and must be dispatched to with ``scx_bpf_dispatch()``.  See the
-function documentation and usage in ``tools/sched_ext/scx_simple.bpf.c`` for
-more information.
+dispatching, and must be dispatched to with ``scx_bpf_dsq_insert()``. See
+the function documentation and usage in ``tools/sched_ext/scx_simple.bpf.c``
+for more information.
 
 Where to Look
 =============
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 5dcb0c1c49ea..8c4f588f54e4 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -220,10 +220,10 @@ struct sched_ext_ops {
 	 * dispatch. While an explicit custom mechanism can be added,
 	 * select_cpu() serves as the default way to wake up idle CPUs.
 	 *
-	 * @p may be dispatched directly by calling scx_bpf_dispatch(). If @p
-	 * is dispatched, the ops.enqueue() callback will be skipped. Finally,
-	 * if @p is dispatched to SCX_DSQ_LOCAL, it will be dispatched to the
-	 * local DSQ of whatever CPU is returned by this callback.
+	 * @p may be inserted into a DSQ directly by calling
+	 * scx_bpf_dsq_insert(). If so, the ops.enqueue() will be skipped.
+	 * Directly inserting into %SCX_DSQ_LOCAL will put @p in the local DSQ
+	 * of the CPU returned by this operation.
 	 *
 	 * Note that select_cpu() is never called for tasks that can only run
 	 * on a single CPU or tasks with migration disabled, as they don't have
@@ -237,12 +237,12 @@ struct sched_ext_ops {
 	 * @p: task being enqueued
 	 * @enq_flags: %SCX_ENQ_*
 	 *
-	 * @p is ready to run. Dispatch directly by calling scx_bpf_dispatch()
-	 * or enqueue on the BPF scheduler. If not directly dispatched, the bpf
-	 * scheduler owns @p and if it fails to dispatch @p, the task will
-	 * stall.
+	 * @p is ready to run. Insert directly into a DSQ by calling
+	 * scx_bpf_dsq_insert() or enqueue on the BPF scheduler. If not directly
+	 * inserted, the bpf scheduler owns @p and if it fails to dispatch @p,
+	 * the task will stall.
 	 *
-	 * If @p was dispatched from ops.select_cpu(), this callback is
+	 * If @p was inserted into a DSQ from ops.select_cpu(), this callback is
 	 * skipped.
 	 */
 	void (*enqueue)(struct task_struct *p, u64 enq_flags);
@@ -270,11 +270,11 @@ struct sched_ext_ops {
 	 *
 	 * Called when a CPU's local dsq is empty. The operation should dispatch
 	 * one or more tasks from the BPF scheduler into the DSQs using
-	 * scx_bpf_dispatch() and/or consume user DSQs into the local DSQ using
-	 * scx_bpf_consume().
+	 * scx_bpf_dsq_insert() and/or consume user DSQs into the local DSQ
+	 * using scx_bpf_consume().
 	 *
-	 * The maximum number of times scx_bpf_dispatch() can be called without
-	 * an intervening scx_bpf_consume() is specified by
+	 * The maximum number of times scx_bpf_dsq_insert() can be called
+	 * without an intervening scx_bpf_consume() is specified by
 	 * ops.dispatch_max_batch. See the comments on top of the two functions
 	 * for more details.
 	 *
@@ -714,7 +714,7 @@ enum scx_enq_flags {
 
 	/*
 	 * Set the following to trigger preemption when calling
-	 * scx_bpf_dispatch() with a local dsq as the target. The slice of the
+	 * scx_bpf_dsq_insert() with a local dsq as the target. The slice of the
 	 * current task is cleared to zero and the CPU is kicked into the
 	 * scheduling path. Implies %SCX_ENQ_HEAD.
 	 */
@@ -2322,7 +2322,7 @@ static bool task_can_run_on_remote_rq(struct task_struct *p, struct rq *rq,
 	/*
 	 * We don't require the BPF scheduler to avoid dispatching to offline
 	 * CPUs mostly for convenience but also because CPUs can go offline
-	 * between scx_bpf_dispatch() calls and here. Trigger error iff the
+	 * between scx_bpf_dsq_insert() calls and here. Trigger error iff the
 	 * picked CPU is outside the allowed mask.
 	 */
 	if (!task_allowed_on_cpu(p, cpu)) {
@@ -2658,7 +2658,7 @@ static void dispatch_to_local_dsq(struct rq *rq, struct scx_dispatch_q *dst_dsq,
  * Dispatching to local DSQs may need to wait for queueing to complete or
  * require rq lock dancing. As we don't wanna do either while inside
  * ops.dispatch() to avoid locking order inversion, we split dispatching into
- * two parts. scx_bpf_dispatch() which is called by ops.dispatch() records the
+ * two parts. scx_bpf_dsq_insert() which is called by ops.dispatch() records the
  * task and its qseq. Once ops.dispatch() returns, this function is called to
  * finish up.
  *
@@ -2690,7 +2690,7 @@ static void finish_dispatch(struct rq *rq, struct task_struct *p,
 		/*
 		 * If qseq doesn't match, @p has gone through at least one
 		 * dispatch/dequeue and re-enqueue cycle between
-		 * scx_bpf_dispatch() and here and we have no claim on it.
+		 * scx_bpf_dsq_insert() and here and we have no claim on it.
 		 */
 		if ((opss & SCX_OPSS_QSEQ_MASK) != qseq_at_dispatch)
 			return;
@@ -6258,7 +6258,7 @@ static const struct btf_kfunc_id_set scx_kfunc_set_select_cpu = {
 	.set			= &scx_kfunc_ids_select_cpu,
 };
 
-static bool scx_dispatch_preamble(struct task_struct *p, u64 enq_flags)
+static bool scx_dsq_insert_preamble(struct task_struct *p, u64 enq_flags)
 {
 	if (!scx_kf_allowed(SCX_KF_ENQUEUE | SCX_KF_DISPATCH))
 		return false;
@@ -6278,7 +6278,8 @@ static bool scx_dispatch_preamble(struct task_struct *p, u64 enq_flags)
 	return true;
 }
 
-static void scx_dispatch_commit(struct task_struct *p, u64 dsq_id, u64 enq_flags)
+static void scx_dsq_insert_commit(struct task_struct *p, u64 dsq_id,
+				  u64 enq_flags)
 {
 	struct scx_dsp_ctx *dspc = this_cpu_ptr(scx_dsp_ctx);
 	struct task_struct *ddsp_task;
@@ -6305,14 +6306,14 @@ static void scx_dispatch_commit(struct task_struct *p, u64 dsq_id, u64 enq_flags
 __bpf_kfunc_start_defs();
 
 /**
- * scx_bpf_dispatch - Dispatch a task into the FIFO queue of a DSQ
- * @p: task_struct to dispatch
- * @dsq_id: DSQ to dispatch to
+ * scx_bpf_dsq_insert - Insert a task into the FIFO queue of a DSQ
+ * @p: task_struct to insert
+ * @dsq_id: DSQ to insert into
  * @slice: duration @p can run for in nsecs, 0 to keep the current value
  * @enq_flags: SCX_ENQ_*
  *
- * Dispatch @p into the FIFO queue of the DSQ identified by @dsq_id. It is safe
- * to call this function spuriously. Can be called from ops.enqueue(),
+ * Insert @p into the FIFO queue of the DSQ identified by @dsq_id. It is safe to
+ * call this function spuriously. Can be called from ops.enqueue(),
  * ops.select_cpu(), and ops.dispatch().
  *
  * When called from ops.select_cpu() or ops.enqueue(), it's for direct dispatch
@@ -6321,14 +6322,14 @@ __bpf_kfunc_start_defs();
  * ops.select_cpu() to be on the target CPU in the first place.
  *
  * When called from ops.select_cpu(), @enq_flags and @dsp_id are stored, and @p
- * will be directly dispatched to the corresponding dispatch queue after
- * ops.select_cpu() returns. If @p is dispatched to SCX_DSQ_LOCAL, it will be
- * dispatched to the local DSQ of the CPU returned by ops.select_cpu().
+ * will be directly inserted into the corresponding dispatch queue after
+ * ops.select_cpu() returns. If @p is inserted into SCX_DSQ_LOCAL, it will be
+ * inserted into the local DSQ of the CPU returned by ops.select_cpu().
  * @enq_flags are OR'd with the enqueue flags on the enqueue path before the
- * task is dispatched.
+ * task is inserted.
  *
  * When called from ops.dispatch(), there are no restrictions on @p or @dsq_id
- * and this function can be called upto ops.dispatch_max_batch times to dispatch
+ * and this function can be called upto ops.dispatch_max_batch times to insert
  * multiple tasks. scx_bpf_dispatch_nr_slots() returns the number of the
  * remaining slots. scx_bpf_consume() flushes the batch and resets the counter.
  *
@@ -6340,10 +6341,10 @@ __bpf_kfunc_start_defs();
  * %SCX_SLICE_INF, @p never expires and the BPF scheduler must kick the CPU with
  * scx_bpf_kick_cpu() to trigger scheduling.
  */
-__bpf_kfunc void scx_bpf_dispatch(struct task_struct *p, u64 dsq_id, u64 slice,
-				  u64 enq_flags)
+__bpf_kfunc void scx_bpf_dsq_insert(struct task_struct *p, u64 dsq_id, u64 slice,
+				    u64 enq_flags)
 {
-	if (!scx_dispatch_preamble(p, enq_flags))
+	if (!scx_dsq_insert_preamble(p, enq_flags))
 		return;
 
 	if (slice)
@@ -6351,30 +6352,38 @@ __bpf_kfunc void scx_bpf_dispatch(struct task_struct *p, u64 dsq_id, u64 slice,
 	else
 		p->scx.slice = p->scx.slice ?: 1;
 
-	scx_dispatch_commit(p, dsq_id, enq_flags);
+	scx_dsq_insert_commit(p, dsq_id, enq_flags);
+}
+
+/* for backward compatibility, will be removed in v6.15 */
+__bpf_kfunc void scx_bpf_dispatch(struct task_struct *p, u64 dsq_id, u64 slice,
+				  u64 enq_flags)
+{
+	printk_deferred_once(KERN_WARNING "sched_ext: scx_bpf_dispatch() renamed to scx_bpf_dsq_insert()");
+	scx_bpf_dsq_insert(p, dsq_id, slice, enq_flags);
 }
 
 /**
- * scx_bpf_dispatch_vtime - Dispatch a task into the vtime priority queue of a DSQ
- * @p: task_struct to dispatch
- * @dsq_id: DSQ to dispatch to
+ * scx_bpf_dsq_insert_vtime - Insert a task into the vtime priority queue of a DSQ
+ * @p: task_struct to insert
+ * @dsq_id: DSQ to insert into
  * @slice: duration @p can run for in nsecs, 0 to keep the current value
  * @vtime: @p's ordering inside the vtime-sorted queue of the target DSQ
  * @enq_flags: SCX_ENQ_*
  *
- * Dispatch @p into the vtime priority queue of the DSQ identified by @dsq_id.
+ * Insert @p into the vtime priority queue of the DSQ identified by @dsq_id.
  * Tasks queued into the priority queue are ordered by @vtime and always
  * consumed after the tasks in the FIFO queue. All other aspects are identical
- * to scx_bpf_dispatch().
+ * to scx_bpf_dsq_insert().
  *
  * @vtime ordering is according to time_before64() which considers wrapping. A
  * numerically larger vtime may indicate an earlier position in the ordering and
  * vice-versa.
  */
-__bpf_kfunc void scx_bpf_dispatch_vtime(struct task_struct *p, u64 dsq_id,
-					u64 slice, u64 vtime, u64 enq_flags)
+__bpf_kfunc void scx_bpf_dsq_insert_vtime(struct task_struct *p, u64 dsq_id,
+					  u64 slice, u64 vtime, u64 enq_flags)
 {
-	if (!scx_dispatch_preamble(p, enq_flags))
+	if (!scx_dsq_insert_preamble(p, enq_flags))
 		return;
 
 	if (slice)
@@ -6384,12 +6393,22 @@ __bpf_kfunc void scx_bpf_dispatch_vtime(struct task_struct *p, u64 dsq_id,
 
 	p->scx.dsq_vtime = vtime;
 
-	scx_dispatch_commit(p, dsq_id, enq_flags | SCX_ENQ_DSQ_PRIQ);
+	scx_dsq_insert_commit(p, dsq_id, enq_flags | SCX_ENQ_DSQ_PRIQ);
+}
+
+/* for backward compatibility, will be removed in v6.15 */
+__bpf_kfunc void scx_bpf_dispatch_vtime(struct task_struct *p, u64 dsq_id,
+					u64 slice, u64 vtime, u64 enq_flags)
+{
+	printk_deferred_once(KERN_WARNING "sched_ext: scx_bpf_dispatch_vtime() renamed to scx_bpf_dsq_insert_vtime()");
+	scx_bpf_dsq_insert_vtime(p, dsq_id, slice, vtime, enq_flags);
 }
 
 __bpf_kfunc_end_defs();
 
 BTF_KFUNCS_START(scx_kfunc_ids_enqueue_dispatch)
+BTF_ID_FLAGS(func, scx_bpf_dsq_insert, KF_RCU)
+BTF_ID_FLAGS(func, scx_bpf_dsq_insert_vtime, KF_RCU)
 BTF_ID_FLAGS(func, scx_bpf_dispatch, KF_RCU)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_vtime, KF_RCU)
 BTF_KFUNCS_END(scx_kfunc_ids_enqueue_dispatch)
@@ -6527,9 +6546,9 @@ __bpf_kfunc void scx_bpf_dispatch_cancel(void)
  * to the current CPU's local DSQ for execution. Can only be called from
  * ops.dispatch().
  *
- * This function flushes the in-flight dispatches from scx_bpf_dispatch() before
- * trying to consume the specified DSQ. It may also grab rq locks and thus can't
- * be called under any BPF locks.
+ * This function flushes the in-flight dispatches from scx_bpf_dsq_insert()
+ * before trying to consume the specified DSQ. It may also grab rq locks and
+ * thus can't be called under any BPF locks.
  *
  * Returns %true if a task has been consumed, %false if there isn't any task to
  * consume.
@@ -6650,7 +6669,7 @@ __bpf_kfunc bool scx_bpf_dispatch_from_dsq(struct bpf_iter_scx_dsq *it__iter,
  * scx_bpf_dispatch_from_dsq_set_vtime() to update.
  *
  * All other aspects are identical to scx_bpf_dispatch_from_dsq(). See
- * scx_bpf_dispatch_vtime() for more information on @vtime.
+ * scx_bpf_dsq_insert_vtime() for more information on @vtime.
  */
 __bpf_kfunc bool scx_bpf_dispatch_vtime_from_dsq(struct bpf_iter_scx_dsq *it__iter,
 						 struct task_struct *p, u64 dsq_id,
diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h
index 248ab790d143..16c7100c69e4 100644
--- a/tools/sched_ext/include/scx/common.bpf.h
+++ b/tools/sched_ext/include/scx/common.bpf.h
@@ -36,8 +36,8 @@ static inline void ___vmlinux_h_sanity_check___(void)
 
 s32 scx_bpf_create_dsq(u64 dsq_id, s32 node) __ksym;
 s32 scx_bpf_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, bool *is_idle) __ksym;
-void scx_bpf_dispatch(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym;
-void scx_bpf_dispatch_vtime(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym;
+void scx_bpf_dsq_insert(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
+void scx_bpf_dsq_insert_vtime(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym __weak;
 u32 scx_bpf_dispatch_nr_slots(void) __ksym;
 void scx_bpf_dispatch_cancel(void) __ksym;
 bool scx_bpf_consume(u64 dsq_id) __ksym;
diff --git a/tools/sched_ext/include/scx/compat.bpf.h b/tools/sched_ext/include/scx/compat.bpf.h
index e5afe9efd3f3..183aa4c6f674 100644
--- a/tools/sched_ext/include/scx/compat.bpf.h
+++ b/tools/sched_ext/include/scx/compat.bpf.h
@@ -34,6 +34,32 @@
 	(bpf_ksym_exists(scx_bpf_dispatch_vtime_from_dsq) ?			\
 	 scx_bpf_dispatch_vtime_from_dsq((it), (p), (dsq_id), (enq_flags)) : false)
 
+/*
+ * v6.13: The verb `dispatch` was too overloaded and confusing. kfuncs are
+ * renamed to unload the verb.
+ *
+ * Build error is triggered if old names are used. New binaries work with both
+ * new and old names. The compat macros will be removed on v6.15 release.
+ */
+void scx_bpf_dispatch___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
+void scx_bpf_dispatch_vtime___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym __weak;
+
+#define scx_bpf_dsq_insert(p, dsq_id, slice, enq_flags)				\
+	(bpf_ksym_exists(scx_bpf_dsq_insert) ?					\
+	 scx_bpf_dsq_insert((p), (dsq_id), (slice), (enq_flags)) :		\
+	 scx_bpf_dispatch___compat((p), (dsq_id), (slice), (enq_flags)))
+
+#define scx_bpf_dsq_insert_vtime(p, dsq_id, slice, vtime, enq_flags)		\
+	(bpf_ksym_exists(scx_bpf_dsq_insert_vtime) ?				\
+	 scx_bpf_dsq_insert_vtime((p), (dsq_id), (slice), (vtime), (enq_flags)) : \
+	 scx_bpf_dispatch_vtime___compat((p), (dsq_id), (slice), (vtime), (enq_flags)))
+
+#define scx_bpf_dispatch(p, dsq_id, slice, enq_flags)				\
+	_Static_assert(false, "scx_bpf_dispatch() renamed to scx_bpf_dsq_insert()")
+
+#define scx_bpf_dispatch_vtime(p, dsq_id, slice, vtime, enq_flags)		\
+	_Static_assert(false, "scx_bpf_dispatch_vtime() renamed to scx_bpf_dsq_insert_vtime()")
+
 /*
  * Define sched_ext_ops. This may be expanded to define multiple variants for
  * backward compatibility. See compat.h::SCX_OPS_LOAD/ATTACH().
diff --git a/tools/sched_ext/scx_central.bpf.c b/tools/sched_ext/scx_central.bpf.c
index 8dd8eb73b6b8..153d9656c75f 100644
--- a/tools/sched_ext/scx_central.bpf.c
+++ b/tools/sched_ext/scx_central.bpf.c
@@ -118,14 +118,14 @@ void BPF_STRUCT_OPS(central_enqueue, struct task_struct *p, u64 enq_flags)
 	 */
 	if ((p->flags & PF_KTHREAD) && p->nr_cpus_allowed == 1) {
 		__sync_fetch_and_add(&nr_locals, 1);
-		scx_bpf_dispatch(p, SCX_DSQ_LOCAL, SCX_SLICE_INF,
-				 enq_flags | SCX_ENQ_PREEMPT);
+		scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, SCX_SLICE_INF,
+				   enq_flags | SCX_ENQ_PREEMPT);
 		return;
 	}
 
 	if (bpf_map_push_elem(&central_q, &pid, 0)) {
 		__sync_fetch_and_add(&nr_overflows, 1);
-		scx_bpf_dispatch(p, FALLBACK_DSQ_ID, SCX_SLICE_INF, enq_flags);
+		scx_bpf_dsq_insert(p, FALLBACK_DSQ_ID, SCX_SLICE_INF, enq_flags);
 		return;
 	}
 
@@ -158,7 +158,7 @@ static bool dispatch_to_cpu(s32 cpu)
 		 */
 		if (!bpf_cpumask_test_cpu(cpu, p->cpus_ptr)) {
 			__sync_fetch_and_add(&nr_mismatches, 1);
-			scx_bpf_dispatch(p, FALLBACK_DSQ_ID, SCX_SLICE_INF, 0);
+			scx_bpf_dsq_insert(p, FALLBACK_DSQ_ID, SCX_SLICE_INF, 0);
 			bpf_task_release(p);
 			/*
 			 * We might run out of dispatch buffer slots if we continue dispatching
@@ -172,7 +172,7 @@ static bool dispatch_to_cpu(s32 cpu)
 		}
 
 		/* dispatch to local and mark that @cpu doesn't need more */
-		scx_bpf_dispatch(p, SCX_DSQ_LOCAL_ON | cpu, SCX_SLICE_INF, 0);
+		scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL_ON | cpu, SCX_SLICE_INF, 0);
 
 		if (cpu != central_cpu)
 			scx_bpf_kick_cpu(cpu, SCX_KICK_IDLE);
diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
index b722baf6da4b..4dcb6c747b46 100644
--- a/tools/sched_ext/scx_flatcg.bpf.c
+++ b/tools/sched_ext/scx_flatcg.bpf.c
@@ -341,7 +341,7 @@ s32 BPF_STRUCT_OPS(fcg_select_cpu, struct task_struct *p, s32 prev_cpu, u64 wake
 	if (is_idle) {
 		set_bypassed_at(p, taskc);
 		stat_inc(FCG_STAT_LOCAL);
-		scx_bpf_dispatch(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, 0);
+		scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, 0);
 	}
 
 	return cpu;
@@ -377,10 +377,12 @@ void BPF_STRUCT_OPS(fcg_enqueue, struct task_struct *p, u64 enq_flags)
 		 */
 		if (p->nr_cpus_allowed == 1 && (p->flags & PF_KTHREAD)) {
 			stat_inc(FCG_STAT_LOCAL);
-			scx_bpf_dispatch(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, enq_flags);
+			scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL,
+					   enq_flags);
 		} else {
 			stat_inc(FCG_STAT_GLOBAL);
-			scx_bpf_dispatch(p, FALLBACK_DSQ, SCX_SLICE_DFL, enq_flags);
+			scx_bpf_dsq_insert(p, FALLBACK_DSQ, SCX_SLICE_DFL,
+					   enq_flags);
 		}
 		return;
 	}
@@ -391,7 +393,7 @@ void BPF_STRUCT_OPS(fcg_enqueue, struct task_struct *p, u64 enq_flags)
 		goto out_release;
 
 	if (fifo_sched) {
-		scx_bpf_dispatch(p, cgrp->kn->id, SCX_SLICE_DFL, enq_flags);
+		scx_bpf_dsq_insert(p, cgrp->kn->id, SCX_SLICE_DFL, enq_flags);
 	} else {
 		u64 tvtime = p->scx.dsq_vtime;
 
@@ -402,8 +404,8 @@ void BPF_STRUCT_OPS(fcg_enqueue, struct task_struct *p, u64 enq_flags)
 		if (vtime_before(tvtime, cgc->tvtime_now - SCX_SLICE_DFL))
 			tvtime = cgc->tvtime_now - SCX_SLICE_DFL;
 
-		scx_bpf_dispatch_vtime(p, cgrp->kn->id, SCX_SLICE_DFL,
-				       tvtime, enq_flags);
+		scx_bpf_dsq_insert_vtime(p, cgrp->kn->id, SCX_SLICE_DFL,
+					 tvtime, enq_flags);
 	}
 
 	cgrp_enqueued(cgrp, cgc);
diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c
index 5d1f880d1149..65c52cc4fffb 100644
--- a/tools/sched_ext/scx_qmap.bpf.c
+++ b/tools/sched_ext/scx_qmap.bpf.c
@@ -226,7 +226,7 @@ void BPF_STRUCT_OPS(qmap_enqueue, struct task_struct *p, u64 enq_flags)
 	 */
 	if (tctx->force_local) {
 		tctx->force_local = false;
-		scx_bpf_dispatch(p, SCX_DSQ_LOCAL, slice_ns, enq_flags);
+		scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, slice_ns, enq_flags);
 		return;
 	}
 
@@ -234,7 +234,7 @@ void BPF_STRUCT_OPS(qmap_enqueue, struct task_struct *p, u64 enq_flags)
 	if (!(enq_flags & SCX_ENQ_CPU_SELECTED) &&
 	    (cpu = pick_direct_dispatch_cpu(p, scx_bpf_task_cpu(p))) >= 0) {
 		__sync_fetch_and_add(&nr_ddsp_from_enq, 1);
-		scx_bpf_dispatch(p, SCX_DSQ_LOCAL_ON | cpu, slice_ns, enq_flags);
+		scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL_ON | cpu, slice_ns, enq_flags);
 		return;
 	}
 
@@ -247,7 +247,7 @@ void BPF_STRUCT_OPS(qmap_enqueue, struct task_struct *p, u64 enq_flags)
 	if (enq_flags & SCX_ENQ_REENQ) {
 		s32 cpu;
 
-		scx_bpf_dispatch(p, SHARED_DSQ, 0, enq_flags);
+		scx_bpf_dsq_insert(p, SHARED_DSQ, 0, enq_flags);
 		cpu = scx_bpf_pick_idle_cpu(p->cpus_ptr, 0);
 		if (cpu >= 0)
 			scx_bpf_kick_cpu(cpu, SCX_KICK_IDLE);
@@ -262,7 +262,7 @@ void BPF_STRUCT_OPS(qmap_enqueue, struct task_struct *p, u64 enq_flags)
 
 	/* Queue on the selected FIFO. If the FIFO overflows, punt to global. */
 	if (bpf_map_push_elem(ring, &pid, 0)) {
-		scx_bpf_dispatch(p, SHARED_DSQ, slice_ns, enq_flags);
+		scx_bpf_dsq_insert(p, SHARED_DSQ, slice_ns, enq_flags);
 		return;
 	}
 
@@ -385,7 +385,7 @@ void BPF_STRUCT_OPS(qmap_dispatch, s32 cpu, struct task_struct *prev)
 		 */
 		p = bpf_task_from_pid(2);
 		if (p) {
-			scx_bpf_dispatch(p, SCX_DSQ_LOCAL, slice_ns, 0);
+			scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, slice_ns, 0);
 			bpf_task_release(p);
 			return;
 		}
@@ -431,7 +431,7 @@ void BPF_STRUCT_OPS(qmap_dispatch, s32 cpu, struct task_struct *prev)
 			update_core_sched_head_seq(p);
 			__sync_fetch_and_add(&nr_dispatched, 1);
 
-			scx_bpf_dispatch(p, SHARED_DSQ, slice_ns, 0);
+			scx_bpf_dsq_insert(p, SHARED_DSQ, slice_ns, 0);
 			bpf_task_release(p);
 
 			batch--;
diff --git a/tools/sched_ext/scx_simple.bpf.c b/tools/sched_ext/scx_simple.bpf.c
index ed7e8d535fc5..ce86a4a690b5 100644
--- a/tools/sched_ext/scx_simple.bpf.c
+++ b/tools/sched_ext/scx_simple.bpf.c
@@ -31,10 +31,10 @@ UEI_DEFINE(uei);
 
 /*
  * Built-in DSQs such as SCX_DSQ_GLOBAL cannot be used as priority queues
- * (meaning, cannot be dispatched to with scx_bpf_dispatch_vtime()). We
+ * (meaning, cannot be dispatched to with scx_bpf_dsq_insert_vtime()). We
  * therefore create a separate DSQ with ID 0 that we dispatch to and consume
- * from. If scx_simple only supported global FIFO scheduling, then we could
- * just use SCX_DSQ_GLOBAL.
+ * from. If scx_simple only supported global FIFO scheduling, then we could just
+ * use SCX_DSQ_GLOBAL.
  */
 #define SHARED_DSQ 0
 
@@ -65,7 +65,7 @@ s32 BPF_STRUCT_OPS(simple_select_cpu, struct task_struct *p, s32 prev_cpu, u64 w
 	cpu = scx_bpf_select_cpu_dfl(p, prev_cpu, wake_flags, &is_idle);
 	if (is_idle) {
 		stat_inc(0);	/* count local queueing */
-		scx_bpf_dispatch(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, 0);
+		scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, 0);
 	}
 
 	return cpu;
@@ -76,7 +76,7 @@ void BPF_STRUCT_OPS(simple_enqueue, struct task_struct *p, u64 enq_flags)
 	stat_inc(1);	/* count global queueing */
 
 	if (fifo_sched) {
-		scx_bpf_dispatch(p, SHARED_DSQ, SCX_SLICE_DFL, enq_flags);
+		scx_bpf_dsq_insert(p, SHARED_DSQ, SCX_SLICE_DFL, enq_flags);
 	} else {
 		u64 vtime = p->scx.dsq_vtime;
 
@@ -87,8 +87,8 @@ void BPF_STRUCT_OPS(simple_enqueue, struct task_struct *p, u64 enq_flags)
 		if (vtime_before(vtime, vtime_now - SCX_SLICE_DFL))
 			vtime = vtime_now - SCX_SLICE_DFL;
 
-		scx_bpf_dispatch_vtime(p, SHARED_DSQ, SCX_SLICE_DFL, vtime,
-				       enq_flags);
+		scx_bpf_dsq_insert_vtime(p, SHARED_DSQ, SCX_SLICE_DFL, vtime,
+					 enq_flags);
 	}
 }
 
-- 
2.47.0

[PATCH 2/3] sched_ext: Rename scx_bpf_consume() to scx_bpf_dsq_move_to_local()

[Tejun Heo]

In sched_ext API, a repeatedly reported pain point is the overuse of the
verb "dispatch" and confusion around "consume":

- ops.dispatch()
- scx_bpf_dispatch[_vtime]()
- scx_bpf_consume()
- scx_bpf_dispatch[_vtime]_from_dsq*()

This overloading of the term is historical. Originally, there were only
built-in DSQs and moving a task into a DSQ always dispatched it for
execution. Using the verb "dispatch" for the kfuncs to move tasks into these
DSQs made sense.

Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
from a non-local DSQ to a local DSQ and this operation was named "consume".
This was already confusing as a task could be dispatched to a user DSQ from
ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
user DSQ.

Clean up the API with the following renames:

1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()

This patch performs the second rename. Compatibility is maintained by:

- The previous kfunc names are still provided by the kernel so that old
  binaries can run. Kernel generates a warning when the old names are used.

- compat.bpf.h provides wrappers for the new names which automatically fall
  back to the old names when running on older kernels. They also trigger
  build error if old names are used for new builds.

The compat features will be dropped after v6.15.

v2: Comment and documentation updates.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrea Righi <arighi@nvidia.com>
Cc: Changwoo Min <multics69@gmail.com>
Cc: Johannes Bechberger <me@mostlynerdless.de>
Cc: Giovanni Gherdovich <ggherdovich@suse.com>
Cc: Dan Schatzberg <dschatzberg@meta.com>
Cc: Ming Yang <yougmark94@gmail.com>
---
 Documentation/scheduler/sched-ext.rst    | 21 ++++++-----
 kernel/sched/ext.c                       | 45 +++++++++++++++---------
 tools/sched_ext/include/scx/common.bpf.h |  2 +-
 tools/sched_ext/include/scx/compat.bpf.h | 11 ++++++
 tools/sched_ext/scx_central.bpf.c        |  4 +--
 tools/sched_ext/scx_flatcg.bpf.c         |  6 ++--
 tools/sched_ext/scx_qmap.bpf.c           |  4 +--
 tools/sched_ext/scx_simple.bpf.c         |  2 +-
 8 files changed, 58 insertions(+), 37 deletions(-)

diff --git a/Documentation/scheduler/sched-ext.rst b/Documentation/scheduler/sched-ext.rst
index ee4af97701bf..6cb8b676ce03 100644
--- a/Documentation/scheduler/sched-ext.rst
+++ b/Documentation/scheduler/sched-ext.rst
@@ -203,13 +203,12 @@ an arbitrary number of dsq's using ``scx_bpf_create_dsq()`` and
 ``scx_bpf_destroy_dsq()``.
 
 A CPU always executes a task from its local DSQ. A task is "inserted" into a
-DSQ. A non-local DSQ is "consumed" to transfer a task to the consuming CPU's
-local DSQ.
+DSQ. A task in a non-local DSQ is "move"d into the target CPU's local DSQ.
 
 When a CPU is looking for the next task to run, if the local DSQ is not
-empty, the first task is picked. Otherwise, the CPU tries to consume the
-global DSQ. If that doesn't yield a runnable task either, ``ops.dispatch()``
-is invoked.
+empty, the first task is picked. Otherwise, the CPU tries to move a task
+from the global DSQ. If that doesn't yield a runnable task either,
+``ops.dispatch()`` is invoked.
 
 Scheduling Cycle
 ----------------
@@ -265,15 +264,15 @@ The following briefly shows how a waking task is scheduled and executed.
      rather than performing them immediately. There can be up to
      ``ops.dispatch_max_batch`` pending tasks.
 
-   * ``scx_bpf_consume()`` tranfers a task from the specified non-local DSQ
-     to the dispatching DSQ. This function cannot be called with any BPF
-     locks held. ``scx_bpf_consume()`` flushes the pending dispatched tasks
-     before trying to consume the specified DSQ.
+   * ``scx_bpf_move_to_local()`` moves a task from the specified non-local
+     DSQ to the dispatching DSQ. This function cannot be called with any BPF
+     locks held. ``scx_bpf_move_to_local()`` flushes the pending insertions
+     tasks before trying to move from the specified DSQ.
 
 4. After ``ops.dispatch()`` returns, if there are tasks in the local DSQ,
    the CPU runs the first one. If empty, the following steps are taken:
 
-   * Try to consume the global DSQ. If successful, run the task.
+   * Try to move from the global DSQ. If successful, run the task.
 
    * If ``ops.dispatch()`` has dispatched any tasks, retry #3.
 
@@ -286,7 +285,7 @@ Note that the BPF scheduler can always choose to dispatch tasks immediately
 in ``ops.enqueue()`` as illustrated in the above simple example. If only the
 built-in DSQs are used, there is no need to implement ``ops.dispatch()`` as
 a task is never queued on the BPF scheduler and both the local and global
-DSQs are consumed automatically.
+DSQs are executed automatically.
 
 ``scx_bpf_dsq_insert()`` inserts the task on the FIFO of the target DSQ. Use
 ``scx_bpf_dsq_insert_vtime()`` for the priority queue. Internal DSQs such as
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 8c4f588f54e4..929475f9b1cd 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -264,17 +264,17 @@ struct sched_ext_ops {
 	void (*dequeue)(struct task_struct *p, u64 deq_flags);
 
 	/**
-	 * dispatch - Dispatch tasks from the BPF scheduler and/or consume DSQs
+	 * dispatch - Dispatch tasks from the BPF scheduler and/or user DSQs
 	 * @cpu: CPU to dispatch tasks for
 	 * @prev: previous task being switched out
 	 *
 	 * Called when a CPU's local dsq is empty. The operation should dispatch
 	 * one or more tasks from the BPF scheduler into the DSQs using
-	 * scx_bpf_dsq_insert() and/or consume user DSQs into the local DSQ
-	 * using scx_bpf_consume().
+	 * scx_bpf_dsq_insert() and/or move from user DSQs into the local DSQ
+	 * using scx_bpf_dsq_move_to_local().
 	 *
 	 * The maximum number of times scx_bpf_dsq_insert() can be called
-	 * without an intervening scx_bpf_consume() is specified by
+	 * without an intervening scx_bpf_dsq_move_to_local() is specified by
 	 * ops.dispatch_max_batch. See the comments on top of the two functions
 	 * for more details.
 	 *
@@ -282,7 +282,7 @@ struct sched_ext_ops {
 	 * @prev is still runnable as indicated by set %SCX_TASK_QUEUED in
 	 * @prev->scx.flags, it is not enqueued yet and will be enqueued after
 	 * ops.dispatch() returns. To keep executing @prev, return without
-	 * dispatching or consuming any tasks. Also see %SCX_OPS_ENQ_LAST.
+	 * dispatching or moving any tasks. Also see %SCX_OPS_ENQ_LAST.
 	 */
 	void (*dispatch)(s32 cpu, struct task_struct *prev);
 
@@ -6372,13 +6372,17 @@ __bpf_kfunc void scx_bpf_dispatch(struct task_struct *p, u64 dsq_id, u64 slice,
  * @enq_flags: SCX_ENQ_*
  *
  * Insert @p into the vtime priority queue of the DSQ identified by @dsq_id.
- * Tasks queued into the priority queue are ordered by @vtime and always
- * consumed after the tasks in the FIFO queue. All other aspects are identical
- * to scx_bpf_dsq_insert().
+ * Tasks queued into the priority queue are ordered by @vtime. All other aspects
+ * are identical to scx_bpf_dsq_insert().
  *
  * @vtime ordering is according to time_before64() which considers wrapping. A
  * numerically larger vtime may indicate an earlier position in the ordering and
  * vice-versa.
+ *
+ * A DSQ can only be used as a FIFO or priority queue at any given time and this
+ * function must not be called on a DSQ which already has one or more FIFO tasks
+ * queued and vice-versa. Also, the built-in DSQs (SCX_DSQ_LOCAL and
+ * SCX_DSQ_GLOBAL) cannot be used as priority queues.
  */
 __bpf_kfunc void scx_bpf_dsq_insert_vtime(struct task_struct *p, u64 dsq_id,
 					  u64 slice, u64 vtime, u64 enq_flags)
@@ -6539,21 +6543,20 @@ __bpf_kfunc void scx_bpf_dispatch_cancel(void)
 }
 
 /**
- * scx_bpf_consume - Transfer a task from a DSQ to the current CPU's local DSQ
- * @dsq_id: DSQ to consume
+ * scx_bpf_dsq_move_to_local - move a task from a DSQ to the current CPU's local DSQ
+ * @dsq_id: DSQ to move task from
  *
- * Consume a task from the non-local DSQ identified by @dsq_id and transfer it
- * to the current CPU's local DSQ for execution. Can only be called from
- * ops.dispatch().
+ * Move a task from the non-local DSQ identified by @dsq_id to the current CPU's
+ * local DSQ for execution. Can only be called from ops.dispatch().
  *
  * This function flushes the in-flight dispatches from scx_bpf_dsq_insert()
- * before trying to consume the specified DSQ. It may also grab rq locks and
+ * before trying to move from the specified DSQ. It may also grab rq locks and
  * thus can't be called under any BPF locks.
  *
- * Returns %true if a task has been consumed, %false if there isn't any task to
- * consume.
+ * Returns %true if a task has been moved, %false if there isn't any task to
+ * move.
  */
-__bpf_kfunc bool scx_bpf_consume(u64 dsq_id)
+__bpf_kfunc bool scx_bpf_dsq_move_to_local(u64 dsq_id)
 {
 	struct scx_dsp_ctx *dspc = this_cpu_ptr(scx_dsp_ctx);
 	struct scx_dispatch_q *dsq;
@@ -6583,6 +6586,13 @@ __bpf_kfunc bool scx_bpf_consume(u64 dsq_id)
 	}
 }
 
+/* for backward compatibility, will be removed in v6.15 */
+__bpf_kfunc bool scx_bpf_consume(u64 dsq_id)
+{
+	printk_deferred_once(KERN_WARNING "sched_ext: scx_bpf_consume() renamed to scx_bpf_dsq_move_to_local()");
+	return scx_bpf_dsq_move_to_local(dsq_id);
+}
+
 /**
  * scx_bpf_dispatch_from_dsq_set_slice - Override slice when dispatching from DSQ
  * @it__iter: DSQ iterator in progress
@@ -6684,6 +6694,7 @@ __bpf_kfunc_end_defs();
 BTF_KFUNCS_START(scx_kfunc_ids_dispatch)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_nr_slots)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_cancel)
+BTF_ID_FLAGS(func, scx_bpf_dsq_move_to_local)
 BTF_ID_FLAGS(func, scx_bpf_consume)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_from_dsq_set_slice)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_from_dsq_set_vtime)
diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h
index 16c7100c69e4..535377649a22 100644
--- a/tools/sched_ext/include/scx/common.bpf.h
+++ b/tools/sched_ext/include/scx/common.bpf.h
@@ -40,7 +40,7 @@ void scx_bpf_dsq_insert(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_fl
 void scx_bpf_dsq_insert_vtime(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym __weak;
 u32 scx_bpf_dispatch_nr_slots(void) __ksym;
 void scx_bpf_dispatch_cancel(void) __ksym;
-bool scx_bpf_consume(u64 dsq_id) __ksym;
+bool scx_bpf_dsq_move_to_local(u64 dsq_id) __ksym;
 void scx_bpf_dispatch_from_dsq_set_slice(struct bpf_iter_scx_dsq *it__iter, u64 slice) __ksym __weak;
 void scx_bpf_dispatch_from_dsq_set_vtime(struct bpf_iter_scx_dsq *it__iter, u64 vtime) __ksym __weak;
 bool scx_bpf_dispatch_from_dsq(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
diff --git a/tools/sched_ext/include/scx/compat.bpf.h b/tools/sched_ext/include/scx/compat.bpf.h
index 183aa4c6f674..c00ed24a8721 100644
--- a/tools/sched_ext/include/scx/compat.bpf.h
+++ b/tools/sched_ext/include/scx/compat.bpf.h
@@ -43,6 +43,7 @@
  */
 void scx_bpf_dispatch___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
 void scx_bpf_dispatch_vtime___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym __weak;
+bool scx_bpf_consume___compat(u64 dsq_id) __ksym __weak;
 
 #define scx_bpf_dsq_insert(p, dsq_id, slice, enq_flags)				\
 	(bpf_ksym_exists(scx_bpf_dsq_insert) ?					\
@@ -54,12 +55,22 @@ void scx_bpf_dispatch_vtime___compat(struct task_struct *p, u64 dsq_id, u64 slic
 	 scx_bpf_dsq_insert_vtime((p), (dsq_id), (slice), (vtime), (enq_flags)) : \
 	 scx_bpf_dispatch_vtime___compat((p), (dsq_id), (slice), (vtime), (enq_flags)))
 
+#define scx_bpf_dsq_move_to_local(dsq_id)					\
+	(bpf_ksym_exists(scx_bpf_dsq_move_to_local) ?				\
+	 scx_bpf_dsq_move_to_local((dsq_id)) :					\
+	 scx_bpf_consume___compat((dsq_id)))
+
 #define scx_bpf_dispatch(p, dsq_id, slice, enq_flags)				\
 	_Static_assert(false, "scx_bpf_dispatch() renamed to scx_bpf_dsq_insert()")
 
 #define scx_bpf_dispatch_vtime(p, dsq_id, slice, vtime, enq_flags)		\
 	_Static_assert(false, "scx_bpf_dispatch_vtime() renamed to scx_bpf_dsq_insert_vtime()")
 
+#define scx_bpf_consume(dsq_id) ({						\
+	_Static_assert(false, "scx_bpf_consume() renamed to scx_bpf_dsq_move_to_local()"); \
+	false;									\
+})
+
 /*
  * Define sched_ext_ops. This may be expanded to define multiple variants for
  * backward compatibility. See compat.h::SCX_OPS_LOAD/ATTACH().
diff --git a/tools/sched_ext/scx_central.bpf.c b/tools/sched_ext/scx_central.bpf.c
index 153d9656c75f..e6fad6211f6c 100644
--- a/tools/sched_ext/scx_central.bpf.c
+++ b/tools/sched_ext/scx_central.bpf.c
@@ -219,13 +219,13 @@ void BPF_STRUCT_OPS(central_dispatch, s32 cpu, struct task_struct *prev)
 		}
 
 		/* look for a task to run on the central CPU */
-		if (scx_bpf_consume(FALLBACK_DSQ_ID))
+		if (scx_bpf_dsq_move_to_local(FALLBACK_DSQ_ID))
 			return;
 		dispatch_to_cpu(central_cpu);
 	} else {
 		bool *gimme;
 
-		if (scx_bpf_consume(FALLBACK_DSQ_ID))
+		if (scx_bpf_dsq_move_to_local(FALLBACK_DSQ_ID))
 			return;
 
 		gimme = ARRAY_ELEM_PTR(cpu_gimme_task, cpu, nr_cpu_ids);
diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
index 4dcb6c747b46..4e3afcd260bf 100644
--- a/tools/sched_ext/scx_flatcg.bpf.c
+++ b/tools/sched_ext/scx_flatcg.bpf.c
@@ -665,7 +665,7 @@ static bool try_pick_next_cgroup(u64 *cgidp)
 		goto out_free;
 	}
 
-	if (!scx_bpf_consume(cgid)) {
+	if (!scx_bpf_dsq_move_to_local(cgid)) {
 		bpf_cgroup_release(cgrp);
 		stat_inc(FCG_STAT_PNC_EMPTY);
 		goto out_stash;
@@ -745,7 +745,7 @@ void BPF_STRUCT_OPS(fcg_dispatch, s32 cpu, struct task_struct *prev)
 		goto pick_next_cgroup;
 
 	if (vtime_before(now, cpuc->cur_at + cgrp_slice_ns)) {
-		if (scx_bpf_consume(cpuc->cur_cgid)) {
+		if (scx_bpf_dsq_move_to_local(cpuc->cur_cgid)) {
 			stat_inc(FCG_STAT_CNS_KEEP);
 			return;
 		}
@@ -785,7 +785,7 @@ void BPF_STRUCT_OPS(fcg_dispatch, s32 cpu, struct task_struct *prev)
 pick_next_cgroup:
 	cpuc->cur_at = now;
 
-	if (scx_bpf_consume(FALLBACK_DSQ)) {
+	if (scx_bpf_dsq_move_to_local(FALLBACK_DSQ)) {
 		cpuc->cur_cgid = 0;
 		return;
 	}
diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c
index 65c52cc4fffb..08f121252c56 100644
--- a/tools/sched_ext/scx_qmap.bpf.c
+++ b/tools/sched_ext/scx_qmap.bpf.c
@@ -374,7 +374,7 @@ void BPF_STRUCT_OPS(qmap_dispatch, s32 cpu, struct task_struct *prev)
 	if (dispatch_highpri(false))
 		return;
 
-	if (!nr_highpri_queued && scx_bpf_consume(SHARED_DSQ))
+	if (!nr_highpri_queued && scx_bpf_dsq_move_to_local(SHARED_DSQ))
 		return;
 
 	if (dsp_inf_loop_after && nr_dispatched > dsp_inf_loop_after) {
@@ -439,7 +439,7 @@ void BPF_STRUCT_OPS(qmap_dispatch, s32 cpu, struct task_struct *prev)
 			if (!batch || !scx_bpf_dispatch_nr_slots()) {
 				if (dispatch_highpri(false))
 					return;
-				scx_bpf_consume(SHARED_DSQ);
+				scx_bpf_dsq_move_to_local(SHARED_DSQ);
 				return;
 			}
 			if (!cpuc->dsp_cnt)
diff --git a/tools/sched_ext/scx_simple.bpf.c b/tools/sched_ext/scx_simple.bpf.c
index ce86a4a690b5..31f915b286c6 100644
--- a/tools/sched_ext/scx_simple.bpf.c
+++ b/tools/sched_ext/scx_simple.bpf.c
@@ -94,7 +94,7 @@ void BPF_STRUCT_OPS(simple_enqueue, struct task_struct *p, u64 enq_flags)
 
 void BPF_STRUCT_OPS(simple_dispatch, s32 cpu, struct task_struct *prev)
 {
-	scx_bpf_consume(SHARED_DSQ);
+	scx_bpf_dsq_move_to_local(SHARED_DSQ);
 }
 
 void BPF_STRUCT_OPS(simple_running, struct task_struct *p)
-- 
2.47.0

[PATCH 3/3] sched_ext: Rename scx_bpf_dispatch[_vtime]_from_dsq*() -> scx_bpf_dsq_move[_vtime]*()

[Tejun Heo]

In sched_ext API, a repeatedly reported pain point is the overuse of the
verb "dispatch" and confusion around "consume":

- ops.dispatch()
- scx_bpf_dispatch[_vtime]()
- scx_bpf_consume()
- scx_bpf_dispatch[_vtime]_from_dsq*()

This overloading of the term is historical. Originally, there were only
built-in DSQs and moving a task into a DSQ always dispatched it for
execution. Using the verb "dispatch" for the kfuncs to move tasks into these
DSQs made sense.

Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
from a non-local DSQ to a local DSQ and this operation was named "consume".
This was already confusing as a task could be dispatched to a user DSQ from
ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
user DSQ.

Clean up the API with the following renames:

1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()

This patch performs the third set of renames. Compatibility is maintained
by:

- The previous kfunc names are still provided by the kernel so that old
  binaries can run. Kernel generates a warning when the old names are used.

- compat.bpf.h provides wrappers for the new names which automatically fall
  back to the old names when running on older kernels. They also trigger
  build error if old names are used for new builds.

- scx_bpf_dispatch[_vtime]_from_dsq*() were already wrapped in __COMPAT
  macros as they were introduced during v6.12 cycle. Wrap new API in
  __COMPAT macros too and trigger build errors on both __COMPAT prefixed and
  naked usages of the old names.

The compat features will be dropped after v6.15.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrea Righi <arighi@nvidia.com>
Cc: Changwoo Min <multics69@gmail.com>
Cc: Johannes Bechberger <me@mostlynerdless.de>
Cc: Giovanni Gherdovich <ggherdovich@suse.com>
Cc: Dan Schatzberg <dschatzberg@meta.com>
Cc: Ming Yang <yougmark94@gmail.com>
---
 kernel/sched/ext.c                       | 97 +++++++++++++++++-------
 tools/sched_ext/include/scx/common.bpf.h | 12 +--
 tools/sched_ext/include/scx/compat.bpf.h | 82 ++++++++++++++++----
 tools/sched_ext/scx_qmap.bpf.c           | 20 ++---
 4 files changed, 152 insertions(+), 59 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 929475f9b1cd..5081fbdab74d 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -6422,9 +6422,8 @@ static const struct btf_kfunc_id_set scx_kfunc_set_enqueue_dispatch = {
 	.set			= &scx_kfunc_ids_enqueue_dispatch,
 };
 
-static bool scx_dispatch_from_dsq(struct bpf_iter_scx_dsq_kern *kit,
-				  struct task_struct *p, u64 dsq_id,
-				  u64 enq_flags)
+static bool scx_dsq_move(struct bpf_iter_scx_dsq_kern *kit,
+			 struct task_struct *p, u64 dsq_id, u64 enq_flags)
 {
 	struct scx_dispatch_q *src_dsq = kit->dsq, *dst_dsq;
 	struct rq *this_rq, *src_rq, *locked_rq;
@@ -6594,16 +6593,16 @@ __bpf_kfunc bool scx_bpf_consume(u64 dsq_id)
 }
 
 /**
- * scx_bpf_dispatch_from_dsq_set_slice - Override slice when dispatching from DSQ
+ * scx_bpf_dsq_move_set_slice - Override slice when moving between DSQs
  * @it__iter: DSQ iterator in progress
- * @slice: duration the dispatched task can run for in nsecs
+ * @slice: duration the moved task can run for in nsecs
  *
- * Override the slice of the next task that will be dispatched from @it__iter
- * using scx_bpf_dispatch_from_dsq[_vtime](). If this function is not called,
- * the previous slice duration is kept.
+ * Override the slice of the next task that will be moved from @it__iter using
+ * scx_bpf_dsq_move[_vtime](). If this function is not called, the previous
+ * slice duration is kept.
  */
-__bpf_kfunc void scx_bpf_dispatch_from_dsq_set_slice(
-				struct bpf_iter_scx_dsq *it__iter, u64 slice)
+__bpf_kfunc void scx_bpf_dsq_move_set_slice(struct bpf_iter_scx_dsq *it__iter,
+					    u64 slice)
 {
 	struct bpf_iter_scx_dsq_kern *kit = (void *)it__iter;
 
@@ -6611,18 +6610,26 @@ __bpf_kfunc void scx_bpf_dispatch_from_dsq_set_slice(
 	kit->cursor.flags |= __SCX_DSQ_ITER_HAS_SLICE;
 }
 
+/* for backward compatibility, will be removed in v6.15 */
+__bpf_kfunc void scx_bpf_dispatch_from_dsq_set_slice(
+			struct bpf_iter_scx_dsq *it__iter, u64 slice)
+{
+	printk_deferred_once(KERN_WARNING "sched_ext: scx_bpf_dispatch_from_dsq_set_slice() renamed to scx_bpf_dsq_move_set_slice()");
+	scx_bpf_dsq_move_set_slice(it__iter, slice);
+}
+
 /**
- * scx_bpf_dispatch_from_dsq_set_vtime - Override vtime when dispatching from DSQ
+ * scx_bpf_dsq_move_set_vtime - Override vtime when moving between DSQs
  * @it__iter: DSQ iterator in progress
  * @vtime: task's ordering inside the vtime-sorted queue of the target DSQ
  *
- * Override the vtime of the next task that will be dispatched from @it__iter
- * using scx_bpf_dispatch_from_dsq_vtime(). If this function is not called, the
- * previous slice vtime is kept. If scx_bpf_dispatch_from_dsq() is used to
- * dispatch the next task, the override is ignored and cleared.
+ * Override the vtime of the next task that will be moved from @it__iter using
+ * scx_bpf_dsq_move_vtime(). If this function is not called, the previous slice
+ * vtime is kept. If scx_bpf_dsq_move() is used to dispatch the next task, the
+ * override is ignored and cleared.
  */
-__bpf_kfunc void scx_bpf_dispatch_from_dsq_set_vtime(
-				struct bpf_iter_scx_dsq *it__iter, u64 vtime)
+__bpf_kfunc void scx_bpf_dsq_move_set_vtime(struct bpf_iter_scx_dsq *it__iter,
+					    u64 vtime)
 {
 	struct bpf_iter_scx_dsq_kern *kit = (void *)it__iter;
 
@@ -6630,8 +6637,16 @@ __bpf_kfunc void scx_bpf_dispatch_from_dsq_set_vtime(
 	kit->cursor.flags |= __SCX_DSQ_ITER_HAS_VTIME;
 }
 
+/* for backward compatibility, will be removed in v6.15 */
+__bpf_kfunc void scx_bpf_dispatch_from_dsq_set_vtime(
+			struct bpf_iter_scx_dsq *it__iter, u64 vtime)
+{
+	printk_deferred_once(KERN_WARNING "sched_ext: scx_bpf_dispatch_from_dsq_set_vtime() renamed to scx_bpf_dsq_move_set_vtime()");
+	scx_bpf_dsq_move_set_vtime(it__iter, vtime);
+}
+
 /**
- * scx_bpf_dispatch_from_dsq - Move a task from DSQ iteration to a DSQ
+ * scx_bpf_dsq_move - Move a task from DSQ iteration to a DSQ
  * @it__iter: DSQ iterator in progress
  * @p: task to transfer
  * @dsq_id: DSQ to move @p to
@@ -6646,8 +6661,7 @@ __bpf_kfunc void scx_bpf_dispatch_from_dsq_set_vtime(
  * @p was obtained from the DSQ iteration. @p just has to be on the DSQ and have
  * been queued before the iteration started.
  *
- * @p's slice is kept by default. Use scx_bpf_dispatch_from_dsq_set_slice() to
- * update.
+ * @p's slice is kept by default. Use scx_bpf_dsq_move_set_slice() to update.
  *
  * Can be called from ops.dispatch() or any BPF context which doesn't hold a rq
  * lock (e.g. BPF timers or SYSCALL programs).
@@ -6655,16 +6669,25 @@ __bpf_kfunc void scx_bpf_dispatch_from_dsq_set_vtime(
  * Returns %true if @p has been consumed, %false if @p had already been consumed
  * or dequeued.
  */
+__bpf_kfunc bool scx_bpf_dsq_move(struct bpf_iter_scx_dsq *it__iter,
+				  struct task_struct *p, u64 dsq_id,
+				  u64 enq_flags)
+{
+	return scx_dsq_move((struct bpf_iter_scx_dsq_kern *)it__iter,
+			    p, dsq_id, enq_flags);
+}
+
+/* for backward compatibility, will be removed in v6.15 */
 __bpf_kfunc bool scx_bpf_dispatch_from_dsq(struct bpf_iter_scx_dsq *it__iter,
 					   struct task_struct *p, u64 dsq_id,
 					   u64 enq_flags)
 {
-	return scx_dispatch_from_dsq((struct bpf_iter_scx_dsq_kern *)it__iter,
-				     p, dsq_id, enq_flags);
+	printk_deferred_once(KERN_WARNING "sched_ext: scx_bpf_dispatch_from_dsq() renamed to scx_bpf_dsq_move()");
+	return scx_bpf_dsq_move(it__iter, p, dsq_id, enq_flags);
 }
 
 /**
- * scx_bpf_dispatch_vtime_from_dsq - Move a task from DSQ iteration to a PRIQ DSQ
+ * scx_bpf_dsq_move_vtime - Move a task from DSQ iteration to a PRIQ DSQ
  * @it__iter: DSQ iterator in progress
  * @p: task to transfer
  * @dsq_id: DSQ to move @p to
@@ -6674,19 +6697,27 @@ __bpf_kfunc bool scx_bpf_dispatch_from_dsq(struct bpf_iter_scx_dsq *it__iter,
  * priority queue of the DSQ specified by @dsq_id. The destination must be a
  * user DSQ as only user DSQs support priority queue.
  *
- * @p's slice and vtime are kept by default. Use
- * scx_bpf_dispatch_from_dsq_set_slice() and
- * scx_bpf_dispatch_from_dsq_set_vtime() to update.
+ * @p's slice and vtime are kept by default. Use scx_bpf_dsq_move_set_slice()
+ * and scx_bpf_dsq_move_set_vtime() to update.
  *
- * All other aspects are identical to scx_bpf_dispatch_from_dsq(). See
+ * All other aspects are identical to scx_bpf_dsq_move(). See
  * scx_bpf_dsq_insert_vtime() for more information on @vtime.
  */
+__bpf_kfunc bool scx_bpf_dsq_move_vtime(struct bpf_iter_scx_dsq *it__iter,
+					struct task_struct *p, u64 dsq_id,
+					u64 enq_flags)
+{
+	return scx_dsq_move((struct bpf_iter_scx_dsq_kern *)it__iter,
+			    p, dsq_id, enq_flags | SCX_ENQ_DSQ_PRIQ);
+}
+
+/* for backward compatibility, will be removed in v6.15 */
 __bpf_kfunc bool scx_bpf_dispatch_vtime_from_dsq(struct bpf_iter_scx_dsq *it__iter,
 						 struct task_struct *p, u64 dsq_id,
 						 u64 enq_flags)
 {
-	return scx_dispatch_from_dsq((struct bpf_iter_scx_dsq_kern *)it__iter,
-				     p, dsq_id, enq_flags | SCX_ENQ_DSQ_PRIQ);
+	printk_deferred_once(KERN_WARNING "sched_ext: scx_bpf_dispatch_from_dsq_vtime() renamed to scx_bpf_dsq_move_vtime()");
+	return scx_bpf_dsq_move_vtime(it__iter, p, dsq_id, enq_flags);
 }
 
 __bpf_kfunc_end_defs();
@@ -6696,6 +6727,10 @@ BTF_ID_FLAGS(func, scx_bpf_dispatch_nr_slots)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_cancel)
 BTF_ID_FLAGS(func, scx_bpf_dsq_move_to_local)
 BTF_ID_FLAGS(func, scx_bpf_consume)
+BTF_ID_FLAGS(func, scx_bpf_dsq_move_set_slice)
+BTF_ID_FLAGS(func, scx_bpf_dsq_move_set_vtime)
+BTF_ID_FLAGS(func, scx_bpf_dsq_move, KF_RCU)
+BTF_ID_FLAGS(func, scx_bpf_dsq_move_vtime, KF_RCU)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_from_dsq_set_slice)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_from_dsq_set_vtime)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_from_dsq, KF_RCU)
@@ -6796,6 +6831,10 @@ __bpf_kfunc_end_defs();
 
 BTF_KFUNCS_START(scx_kfunc_ids_unlocked)
 BTF_ID_FLAGS(func, scx_bpf_create_dsq, KF_SLEEPABLE)
+BTF_ID_FLAGS(func, scx_bpf_dsq_move_set_slice)
+BTF_ID_FLAGS(func, scx_bpf_dsq_move_set_vtime)
+BTF_ID_FLAGS(func, scx_bpf_dsq_move, KF_RCU)
+BTF_ID_FLAGS(func, scx_bpf_dsq_move_vtime, KF_RCU)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_from_dsq_set_slice)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_from_dsq_set_vtime)
 BTF_ID_FLAGS(func, scx_bpf_dispatch_from_dsq, KF_RCU)
diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h
index 535377649a22..2f36b7b6418d 100644
--- a/tools/sched_ext/include/scx/common.bpf.h
+++ b/tools/sched_ext/include/scx/common.bpf.h
@@ -41,10 +41,10 @@ void scx_bpf_dsq_insert_vtime(struct task_struct *p, u64 dsq_id, u64 slice, u64
 u32 scx_bpf_dispatch_nr_slots(void) __ksym;
 void scx_bpf_dispatch_cancel(void) __ksym;
 bool scx_bpf_dsq_move_to_local(u64 dsq_id) __ksym;
-void scx_bpf_dispatch_from_dsq_set_slice(struct bpf_iter_scx_dsq *it__iter, u64 slice) __ksym __weak;
-void scx_bpf_dispatch_from_dsq_set_vtime(struct bpf_iter_scx_dsq *it__iter, u64 vtime) __ksym __weak;
-bool scx_bpf_dispatch_from_dsq(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
-bool scx_bpf_dispatch_vtime_from_dsq(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
+void scx_bpf_dsq_move_set_slice(struct bpf_iter_scx_dsq *it__iter, u64 slice) __ksym;
+void scx_bpf_dsq_move_set_vtime(struct bpf_iter_scx_dsq *it__iter, u64 vtime) __ksym;
+bool scx_bpf_dsq_move(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
+bool scx_bpf_dsq_move_vtime(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
 u32 scx_bpf_reenqueue_local(void) __ksym;
 void scx_bpf_kick_cpu(s32 cpu, u64 flags) __ksym;
 s32 scx_bpf_dsq_nr_queued(u64 dsq_id) __ksym;
@@ -74,8 +74,8 @@ struct rq *scx_bpf_cpu_rq(s32 cpu) __ksym;
 struct cgroup *scx_bpf_task_cgroup(struct task_struct *p) __ksym __weak;
 
 /*
- * Use the following as @it__iter when calling
- * scx_bpf_dispatch[_vtime]_from_dsq() from within bpf_for_each() loops.
+ * Use the following as @it__iter when calling scx_bpf_dsq_move[_vtime]() from
+ * within bpf_for_each() loops.
  */
 #define BPF_FOR_EACH_ITER	(&___it)
 
diff --git a/tools/sched_ext/include/scx/compat.bpf.h b/tools/sched_ext/include/scx/compat.bpf.h
index c00ed24a8721..d56520100a26 100644
--- a/tools/sched_ext/include/scx/compat.bpf.h
+++ b/tools/sched_ext/include/scx/compat.bpf.h
@@ -20,30 +20,24 @@
 	(bpf_ksym_exists(scx_bpf_task_cgroup) ?					\
 	 scx_bpf_task_cgroup((p)) : NULL)
 
-/* v6.12: 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()") */
-#define __COMPAT_scx_bpf_dispatch_from_dsq_set_slice(it, slice)			\
-	(bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_slice) ?			\
-	 scx_bpf_dispatch_from_dsq_set_slice((it), (slice)) : (void)0)
-#define __COMPAT_scx_bpf_dispatch_from_dsq_set_vtime(it, vtime)			\
-	(bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_vtime) ?			\
-	 scx_bpf_dispatch_from_dsq_set_vtime((it), (vtime)) : (void)0)
-#define __COMPAT_scx_bpf_dispatch_from_dsq(it, p, dsq_id, enq_flags)		\
-	(bpf_ksym_exists(scx_bpf_dispatch_from_dsq) ?				\
-	 scx_bpf_dispatch_from_dsq((it), (p), (dsq_id), (enq_flags)) : false)
-#define __COMPAT_scx_bpf_dispatch_vtime_from_dsq(it, p, dsq_id, enq_flags)	\
-	(bpf_ksym_exists(scx_bpf_dispatch_vtime_from_dsq) ?			\
-	 scx_bpf_dispatch_vtime_from_dsq((it), (p), (dsq_id), (enq_flags)) : false)
-
 /*
  * v6.13: The verb `dispatch` was too overloaded and confusing. kfuncs are
  * renamed to unload the verb.
  *
  * Build error is triggered if old names are used. New binaries work with both
  * new and old names. The compat macros will be removed on v6.15 release.
+ *
+ * scx_bpf_dispatch_from_dsq() and friends were added during v6.12 by
+ * 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()").
+ * Preserve __COMPAT macros until v6.15.
  */
 void scx_bpf_dispatch___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
 void scx_bpf_dispatch_vtime___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym __weak;
 bool scx_bpf_consume___compat(u64 dsq_id) __ksym __weak;
+void scx_bpf_dispatch_from_dsq_set_slice___compat(struct bpf_iter_scx_dsq *it__iter, u64 slice) __ksym __weak;
+void scx_bpf_dispatch_from_dsq_set_vtime___compat(struct bpf_iter_scx_dsq *it__iter, u64 vtime) __ksym __weak;
+bool scx_bpf_dispatch_from_dsq___compat(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
+bool scx_bpf_dispatch_vtime_from_dsq___compat(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
 
 #define scx_bpf_dsq_insert(p, dsq_id, slice, enq_flags)				\
 	(bpf_ksym_exists(scx_bpf_dsq_insert) ?					\
@@ -60,6 +54,34 @@ bool scx_bpf_consume___compat(u64 dsq_id) __ksym __weak;
 	 scx_bpf_dsq_move_to_local((dsq_id)) :					\
 	 scx_bpf_consume___compat((dsq_id)))
 
+#define __COMPAT_scx_bpf_dsq_move_set_slice(it__iter, slice)			\
+	(bpf_ksym_exists(scx_bpf_dsq_move_set_slice) ?				\
+	 scx_bpf_dsq_move_set_slice((it__iter), (slice)) :			\
+	 (bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_slice___compat) ?	\
+	  scx_bpf_dispatch_from_dsq_set_slice___compat((it__iter), (slice)) :	\
+	  (void)0))
+
+#define __COMPAT_scx_bpf_dsq_move_set_vtime(it__iter, vtime)			\
+	(bpf_ksym_exists(scx_bpf_dsq_move_set_vtime) ?				\
+	 scx_bpf_dsq_move_set_vtime((it__iter), (vtime)) :			\
+	 (bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_vtime___compat) ?	\
+	  scx_bpf_dispatch_from_dsq_set_vtime___compat((it__iter), (vtime)) :	\
+	  (void) 0))
+
+#define __COMPAT_scx_bpf_dsq_move(it__iter, p, dsq_id, enq_flags)		\
+	(bpf_ksym_exists(scx_bpf_dsq_move) ?					\
+	 scx_bpf_dsq_move((it__iter), (p), (dsq_id), (enq_flags)) :		\
+	 (bpf_ksym_exists(scx_bpf_dispatch_from_dsq___compat) ?			\
+	  scx_bpf_dispatch_from_dsq___compat((it__iter), (p), (dsq_id), (enq_flags)) : \
+	  false))
+
+#define __COMPAT_scx_bpf_dsq_move_vtime(it__iter, p, dsq_id, enq_flags)		\
+	(bpf_ksym_exists(scx_bpf_dsq_move_vtime) ?				\
+	 scx_bpf_dsq_move_vtime((it__iter), (p), (dsq_id), (enq_flags)) :	\
+	 (bpf_ksym_exists(scx_bpf_dispatch_vtime_from_dsq___compat) ?		\
+	  scx_bpf_dispatch_vtime_from_dsq___compat((it__iter), (p), (dsq_id), (enq_flags)) : \
+	  false))
+
 #define scx_bpf_dispatch(p, dsq_id, slice, enq_flags)				\
 	_Static_assert(false, "scx_bpf_dispatch() renamed to scx_bpf_dsq_insert()")
 
@@ -71,6 +93,38 @@ bool scx_bpf_consume___compat(u64 dsq_id) __ksym __weak;
 	false;									\
 })
 
+#define scx_bpf_dispatch_from_dsq_set_slice(it__iter, slice)		\
+	_Static_assert(false, "scx_bpf_dispatch_from_dsq_set_slice() renamed to scx_bpf_dsq_move_set_slice()")
+
+#define scx_bpf_dispatch_from_dsq_set_vtime(it__iter, vtime)		\
+	_Static_assert(false, "scx_bpf_dispatch_from_dsq_set_vtime() renamed to scx_bpf_dsq_move_set_vtime()")
+
+#define scx_bpf_dispatch_from_dsq(it__iter, p, dsq_id, enq_flags) ({	\
+	_Static_assert(false, "scx_bpf_dispatch_from_dsq() renamed to scx_bpf_dsq_move()"); \
+	false;									\
+})
+
+#define scx_bpf_dispatch_vtime_from_dsq(it__iter, p, dsq_id, enq_flags) ({  \
+	_Static_assert(false, "scx_bpf_dispatch_vtime_from_dsq() renamed to scx_bpf_dsq_move_vtime()"); \
+	false;									\
+})
+
+#define __COMPAT_scx_bpf_dispatch_from_dsq_set_slice(it__iter, slice)		\
+	_Static_assert(false, "__COMPAT_scx_bpf_dispatch_from_dsq_set_slice() renamed to __COMPAT_scx_bpf_dsq_move_set_slice()")
+
+#define __COMPAT_scx_bpf_dispatch_from_dsq_set_vtime(it__iter, vtime)		\
+	_Static_assert(false, "__COMPAT_scx_bpf_dispatch_from_dsq_set_vtime() renamed to __COMPAT_scx_bpf_dsq_move_set_vtime()")
+
+#define __COMPAT_scx_bpf_dispatch_from_dsq(it__iter, p, dsq_id, enq_flags) ({	\
+	_Static_assert(false, "__COMPAT_scx_bpf_dispatch_from_dsq() renamed to __COMPAT_scx_bpf_dsq_move()"); \
+	false;									\
+})
+
+#define __COMPAT_scx_bpf_dispatch_vtime_from_dsq(it__iter, p, dsq_id, enq_flags) ({  \
+	_Static_assert(false, "__COMPAT_scx_bpf_dispatch_vtime_from_dsq() renamed to __COMPAT_scx_bpf_dsq_move_vtime()"); \
+	false;									\
+})
+
 /*
  * Define sched_ext_ops. This may be expanded to define multiple variants for
  * backward compatibility. See compat.h::SCX_OPS_LOAD/ATTACH().
diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c
index 08f121252c56..ee264947e0c3 100644
--- a/tools/sched_ext/scx_qmap.bpf.c
+++ b/tools/sched_ext/scx_qmap.bpf.c
@@ -294,10 +294,10 @@ static void update_core_sched_head_seq(struct task_struct *p)
 }
 
 /*
- * To demonstrate the use of scx_bpf_dispatch_from_dsq(), implement silly
- * selective priority boosting mechanism by scanning SHARED_DSQ looking for
- * highpri tasks, moving them to HIGHPRI_DSQ and then consuming them first. This
- * makes minor difference only when dsp_batch is larger than 1.
+ * To demonstrate the use of scx_bpf_dsq_move(), implement silly selective
+ * priority boosting mechanism by scanning SHARED_DSQ looking for highpri tasks,
+ * moving them to HIGHPRI_DSQ and then consuming them first. This makes minor
+ * difference only when dsp_batch is larger than 1.
  *
  * scx_bpf_dispatch[_vtime]_from_dsq() are allowed both from ops.dispatch() and
  * non-rq-lock holding BPF programs. As demonstration, this function is called
@@ -318,11 +318,11 @@ static bool dispatch_highpri(bool from_timer)
 
 		if (tctx->highpri) {
 			/* exercise the set_*() and vtime interface too */
-			__COMPAT_scx_bpf_dispatch_from_dsq_set_slice(
+			__COMPAT_scx_bpf_dsq_move_set_slice(
 				BPF_FOR_EACH_ITER, slice_ns * 2);
-			__COMPAT_scx_bpf_dispatch_from_dsq_set_vtime(
+			__COMPAT_scx_bpf_dsq_move_set_vtime(
 				BPF_FOR_EACH_ITER, highpri_seq++);
-			__COMPAT_scx_bpf_dispatch_vtime_from_dsq(
+			__COMPAT_scx_bpf_dsq_move_vtime(
 				BPF_FOR_EACH_ITER, p, HIGHPRI_DSQ, 0);
 		}
 	}
@@ -340,9 +340,9 @@ static bool dispatch_highpri(bool from_timer)
 		else
 			cpu = scx_bpf_pick_any_cpu(p->cpus_ptr, 0);
 
-		if (__COMPAT_scx_bpf_dispatch_from_dsq(BPF_FOR_EACH_ITER, p,
-						       SCX_DSQ_LOCAL_ON | cpu,
-						       SCX_ENQ_PREEMPT)) {
+		if (__COMPAT_scx_bpf_dsq_move(BPF_FOR_EACH_ITER, p,
+					      SCX_DSQ_LOCAL_ON | cpu,
+					      SCX_ENQ_PREEMPT)) {
 			if (cpu == this_cpu) {
 				dispatched = true;
 				__sync_fetch_and_add(&nr_expedited_local, 1);
-- 
2.47.0

Re: [PATCH 3/3] sched_ext: Rename scx_bpf_dispatch[_vtime]_from_dsq*() -> scx_bpf_dsq_move[_vtime]*()

[Giovanni Gherdovich]

Hello,

On Sun Nov 10, 2024 21:02, Tejun Heo wrote:
> In sched_ext API, a repeatedly reported pain point is the overuse of the
> verb "dispatch" and confusion around "consume": [...]
> 
> Clean up the API with the following renames:
> 
> 1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
> 2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
> 3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()
> 
> This patch performs the third set of renames. Compatibility is maintained
> by: [...]

Thanks Tejun.

For the whole series,

Acked-by: Giovanni Gherdovich <ggherdovich@suse.com>


Giovanni

Re: [PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

[Andrea Righi]

Hi Tejun,

On Sun, Nov 10, 2024 at 10:02:50AM -1000, Tejun Heo wrote:
> Hello,
> 
> [v1] -> v2: Comment and documentation updates.
> 
> In sched_ext API, a repeatedly reported pain point is the overuse of the
> verb "dispatch" and confusion around "consume":
> 
> - ops.dispatch()
> - scx_bpf_dispatch[_vtime]()
> - scx_bpf_consume()
> - scx_bpf_dispatch[_vtime]_from_dsq*()
> 
> This overloading of the term is historical. Originally, there were only
> built-in DSQs and moving a task into a DSQ always dispatched it for
> execution. Using the verb "dispatch" for the kfuncs to move tasks into these
> DSQs made sense.
> 
> Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
> able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
> from a non-local DSQ to a local DSQ and this operation was named "consume".
> This was already confusing as a task could be dispatched to a user DSQ from
> ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
> Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
> as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
> user DSQ.
> 
> Clean up the API with the following renames:
> 
> 1. scx_bpf_dispatch[_vtime]()           -> scx_bpf_dsq_insert[_vtime]()
> 2. scx_bpf_consume()                    -> scx_bpf_dsq_move_to_local()
> 3. scx_bpf_dispatch[_vtime]_from_dsq*() -> scx_bpf_dsq_move[_vtime]*()
> 
> This patchset is on top of sched_ext/for-6.13 72b85bf6a7f6 ("sched_ext:
> scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context") and
> contains the following patches:
> 
>  0001-sched_ext-Rename-scx_bpf_dispatch-_vtime-to-scx_bpf_.patch
>  0002-sched_ext-Rename-scx_bpf_consume-to-scx_bpf_dsq_move.patch
>  0003-sched_ext-Rename-scx_bpf_dispatch-_vtime-_from_dsq-s.patch
> 
> and is always available in the following git branch:
> 
>  git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-api-rename-dispatch-v2
> 
> diffstat follows. Thanks.

Looks good to me, thanks!

Acked-by: Andrea Righi <arighi@nvidia.com>

-Andrea

Re: [PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

[Changwoo Min]

Hello,

On 24. 11. 11. 05:02, Tejun Heo wrote:
> Hello,
> 
> [v1] -> v2: Comment and documentation updates.
> 
> In sched_ext API, a repeatedly reported pain point is the overuse of the
> verb "dispatch" and confusion around "consume":
> 
> - ops.dispatch()
> - scx_bpf_dispatch[_vtime]()
> - scx_bpf_consume()
> - scx_bpf_dispatch[_vtime]_from_dsq*()
> 
> This overloading of the term is historical. Originally, there were only
> built-in DSQs and moving a task into a DSQ always dispatched it for
> execution. Using the verb "dispatch" for the kfuncs to move tasks into these
> DSQs made sense.
> 
> Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
> able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
> from a non-local DSQ to a local DSQ and this operation was named "consume".
> This was already confusing as a task could be dispatched to a user DSQ from
> ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
> Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
> as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
> user DSQ.
> 
> Clean up the API with the following renames:
> 
> 1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
> 2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
> 3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()
> 
> This patchset is on top of sched_ext/for-6.13 72b85bf6a7f6 ("sched_ext:
> scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context") and
> contains the following patches:
> 
>   0001-sched_ext-Rename-scx_bpf_dispatch-_vtime-to-scx_bpf_.patch
>   0002-sched_ext-Rename-scx_bpf_consume-to-scx_bpf_dsq_move.patch
>   0003-sched_ext-Rename-scx_bpf_dispatch-_vtime-_from_dsq-s.patch
> 
> and is always available in the following git branch:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-api-rename-dispatch-v2
> 
> diffstat follows. Thanks.

Looks good to me. Thanks!

Acked-by: Changwoo Min <changwoo@igalia.com>


Regards,
Changwoo Min

Re: [PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

[Johannes Bechberger]

Hello,

On 24. 11. 11. 05:02, Tejun Heo wrote:
•••

> 
> Hello,
>  [v1] -> v2: Comment and documentation updates.
>  In sched_ext API, a repeatedly reported pain point is the overuse of the
>  verb "dispatch" and confusion around "consume":
>  - ops.dispatch()
>  - scx_bpf_dispatch[_vtime]()
>  - scx_bpf_consume()
>  - scx_bpf_dispatch[_vtime]_from_dsq*()
>  This overloading of the term is historical. Originally, there were only
>  built-in DSQs and moving a task into a DSQ always dispatched it for
>  execution. Using the verb "dispatch" for the kfuncs to move tasks into these
>  DSQs made sense.
>  Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
>  able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
>  from a non-local DSQ to a local DSQ and this operation was named "consume".
>  This was already confusing as a task could be dispatched to a user DSQ from
>  ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
>  Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
>  as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
>  user DSQ.
>  Clean up the API with the following renames:
>  1. scx_bpf_dispatch[_vtime]() -> scx_bpf_dsq_insert[_vtime]()
>  2. scx_bpf_consume() -> scx_bpf_dsq_move_to_local()
>  3. scx_bpf_dispatch[_vtime]_from_dsq*() -> scx_bpf_dsq_move[_vtime]*()
>  This patchset is on top of sched_ext/for-6.13 72b85bf6a7f6 ("sched_ext:
>  scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context") and
>  contains the following patches:
>  0001-sched_ext-Rename-scx_bpf_dispatch-_vtime-to-scx_bpf_.patch
>  0002-sched_ext-Rename-scx_bpf_consume-to-scx_bpf_dsq_move.patch
>  0003-sched_ext-Rename-scx_bpf_dispatch-_vtime-_from_dsq-s.patch
>  and is always available in the following git branch:
>  git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git http://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git  scx-api-rename-dispatch-v2
>  diffstat follows. Thanks.
> 

Looks good to me too. Thanks for your effort :)

Acked-by: Johannes Bechberger <me@mostlynerdless.de mailto:me@mostlynerdless.de >

Regards
Johannes Bechberger

Re: [PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

[Tejun Heo]

On Sun, Nov 10, 2024 at 10:02:50AM -1000, Tejun Heo wrote:
...
> Clean up the API with the following renames:
> 
> 1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
> 2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
> 3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()
> 
> This patchset is on top of sched_ext/for-6.13 72b85bf6a7f6 ("sched_ext:
> scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context") and
> contains the following patches:
> 
>  0001-sched_ext-Rename-scx_bpf_dispatch-_vtime-to-scx_bpf_.patch
>  0002-sched_ext-Rename-scx_bpf_consume-to-scx_bpf_dsq_move.patch
>  0003-sched_ext-Rename-scx_bpf_dispatch-_vtime-_from_dsq-s.patch

Applied to sched_ext/for-6.13.

Thanks.

-- 
tejun

Re: [PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

[David Vernet]

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On Sun, Nov 10, 2024 at 10:02:50AM -1000, Tejun Heo wrote:
> Hello,
> 
> [v1] -> v2: Comment and documentation updates.
> 
> In sched_ext API, a repeatedly reported pain point is the overuse of the
> verb "dispatch" and confusion around "consume":
> 
> - ops.dispatch()
> - scx_bpf_dispatch[_vtime]()
> - scx_bpf_consume()
> - scx_bpf_dispatch[_vtime]_from_dsq*()
> 
> This overloading of the term is historical. Originally, there were only
> built-in DSQs and moving a task into a DSQ always dispatched it for
> execution. Using the verb "dispatch" for the kfuncs to move tasks into these
> DSQs made sense.
> 
> Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
> able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
> from a non-local DSQ to a local DSQ and this operation was named "consume".
> This was already confusing as a task could be dispatched to a user DSQ from
> ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
> Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
> as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
> user DSQ.
> 
> Clean up the API with the following renames:
> 
> 1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
> 2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
> 3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()
> 
> This patchset is on top of sched_ext/for-6.13 72b85bf6a7f6 ("sched_ext:
> scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context") and
> contains the following patches:
> 
>  0001-sched_ext-Rename-scx_bpf_dispatch-_vtime-to-scx_bpf_.patch
>  0002-sched_ext-Rename-scx_bpf_consume-to-scx_bpf_dsq_move.patch
>  0003-sched_ext-Rename-scx_bpf_dispatch-_vtime-_from_dsq-s.patch

For the series:

Acked-by: David Vernet <void@manifault.com>

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[PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

[Tejun Heo]

In sched_ext API, a repeatedly reported pain point is the overuse of the
verb "dispatch" and confusion around "consume":

- ops.dispatch()
- scx_bpf_dispatch[_vtime]()
- scx_bpf_consume()
- scx_bpf_dispatch[_vtime]_from_dsq*()

This overloading of the term is historical. Originally, there were only
built-in DSQs and moving a task into a DSQ always dispatched it for
execution. Using the verb "dispatch" for the kfuncs to move tasks into these
DSQs made sense.

Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
from a non-local DSQ to a local DSQ and this operation was named "consume".
This was already confusing as a task could be dispatched to a user DSQ from
ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
user DSQ.

Clean up the API with the following renames:

1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()

This patchset is on top of sched_ext/for-6.13 72b85bf6a7f6 ("sched_ext:
scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context") and
contains the following patches:

 0001-sched_ext-Rename-scx_bpf_dispatch-_vtime-to-scx_bpf_.patch
 0002-sched_ext-Rename-scx_bpf_consume-to-scx_bpf_dsq_move.patch
 0003-sched_ext-Rename-scx_bpf_dispatch-_vtime-_from_dsq-s.patch

and is always available in the following git branch:

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-api-rename-dispatch

diffstat follows. Thanks.

 kernel/sched/ext.c                       |  238 +++++++++++++++++++++++++++++++++--------------------
 tools/sched_ext/include/scx/common.bpf.h |   18 ++--
 tools/sched_ext/include/scx/compat.bpf.h |  117 +++++++++++++++++++++++---
 tools/sched_ext/scx_central.bpf.c        |   14 +--
 tools/sched_ext/scx_flatcg.bpf.c         |   20 ++--
 tools/sched_ext/scx_qmap.bpf.c           |   36 ++++----
 tools/sched_ext/scx_simple.bpf.c         |   16 +--
 7 files changed, 308 insertions(+), 151 deletions(-)

--
tejun

Re: [PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

[Andrea Righi]

Hi Tejun,

On Sat, Nov 09, 2024 at 09:48:29AM -1000, Tejun Heo wrote:
> In sched_ext API, a repeatedly reported pain point is the overuse of the
> verb "dispatch" and confusion around "consume":
> 
> - ops.dispatch()
> - scx_bpf_dispatch[_vtime]()
> - scx_bpf_consume()
> - scx_bpf_dispatch[_vtime]_from_dsq*()
> 
> This overloading of the term is historical. Originally, there were only
> built-in DSQs and moving a task into a DSQ always dispatched it for
> execution. Using the verb "dispatch" for the kfuncs to move tasks into these
> DSQs made sense.
> 
> Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
> able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
> from a non-local DSQ to a local DSQ and this operation was named "consume".
> This was already confusing as a task could be dispatched to a user DSQ from
> ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
> Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
> as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
> user DSQ.
> 
> Clean up the API with the following renames:
> 
> 1. scx_bpf_dispatch[_vtime]()           -> scx_bpf_dsq_insert[_vtime]()
> 2. scx_bpf_consume()                    -> scx_bpf_dsq_move_to_local()
> 3. scx_bpf_dispatch[_vtime]_from_dsq*() -> scx_bpf_dsq_move[_vtime]*()
> 
> This patchset is on top of sched_ext/for-6.13 72b85bf6a7f6 ("sched_ext:
> scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context") and
> contains the following patches:
> 
>  0001-sched_ext-Rename-scx_bpf_dispatch-_vtime-to-scx_bpf_.patch
>  0002-sched_ext-Rename-scx_bpf_consume-to-scx_bpf_dsq_move.patch
>  0003-sched_ext-Rename-scx_bpf_dispatch-_vtime-_from_dsq-s.patch
> 
> and is always available in the following git branch:
> 
>  git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-api-rename-dispatch
> 
> diffstat follows. Thanks.
> 
>  kernel/sched/ext.c                       |  238 +++++++++++++++++++++++++++++++++--------------------
>  tools/sched_ext/include/scx/common.bpf.h |   18 ++--
>  tools/sched_ext/include/scx/compat.bpf.h |  117 +++++++++++++++++++++++---
>  tools/sched_ext/scx_central.bpf.c        |   14 +--
>  tools/sched_ext/scx_flatcg.bpf.c         |   20 ++--
>  tools/sched_ext/scx_qmap.bpf.c           |   36 ++++----
>  tools/sched_ext/scx_simple.bpf.c         |   16 +--
>  7 files changed, 308 insertions(+), 151 deletions(-)

Overall it looks good to me, we should probably update also
Documentation/scheduler/sched-ext.rst.

Thanks,
-Andrea