Merge tag 'sched_ext-for-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Merge commit. Changes below are compared with the first parent: 606489db.
Changes
21 files changed · +690 −160
Only the first 600 diff lines are shown. Download the complete patch.
Documentation/scheduler/sched-ext.rst
View filediff --git a/Documentation/scheduler/sched-ext.rst b/Documentation/scheduler/sched-ext.rst
index 6d83df3..c4672d7 100644
--- a/Documentation/scheduler/sched-ext.rst
+++ b/Documentation/scheduler/sched-ext.rst
@@ -242,9 +242,9 @@ The following briefly shows how a waking task is scheduled and executed.
task was inserted directly from ``ops.select_cpu()``). ``ops.enqueue()``
can make one of the following decisions:
- * 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 insert the task into either the global or a local DSQ by
+ calling ``scx_bpf_dsq_insert()`` with one of the following options:
+ ``SCX_DSQ_GLOBAL``, ``SCX_DSQ_LOCAL``, or ``SCX_DSQ_LOCAL_ON | cpu``.
* Immediately insert the task into a custom DSQ by calling
``scx_bpf_dsq_insert()`` with a DSQ ID which is smaller than 2^63.
kernel/sched/core.c
View filediff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 88a9a51..9011707 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -793,6 +793,7 @@ static void update_rq_clock_task(struct rq *rq, s64 delta)
void update_rq_clock(struct rq *rq)
{
s64 delta;
+ u64 clock;
lockdep_assert_rq_held(rq);
@@ -804,11 +805,14 @@ void update_rq_clock(struct rq *rq)
SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED);
rq->clock_update_flags |= RQCF_UPDATED;
#endif
+ clock = sched_clock_cpu(cpu_of(rq));
+ scx_rq_clock_update(rq, clock);
- delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
+ delta = clock - rq->clock;
if (delta < 0)
return;
rq->clock += delta;
+
update_rq_clock_task(rq, delta);
}
kernel/sched/ext.c
View filediff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 7fee434..8857c07 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -206,7 +206,7 @@ struct scx_dump_ctx {
*/
struct sched_ext_ops {
/**
- * select_cpu - Pick the target CPU for a task which is being woken up
+ * @select_cpu: Pick the target CPU for a task which is being woken up
* @p: task being woken up
* @prev_cpu: the cpu @p was on before sleeping
* @wake_flags: SCX_WAKE_*
@@ -233,7 +233,7 @@ struct sched_ext_ops {
s32 (*select_cpu)(struct task_struct *p, s32 prev_cpu, u64 wake_flags);
/**
- * enqueue - Enqueue a task on the BPF scheduler
+ * @enqueue: Enqueue a task on the BPF scheduler
* @p: task being enqueued
* @enq_flags: %SCX_ENQ_*
*
@@ -248,7 +248,7 @@ struct sched_ext_ops {
void (*enqueue)(struct task_struct *p, u64 enq_flags);
/**
- * dequeue - Remove a task from the BPF scheduler
+ * @dequeue: Remove a task from the BPF scheduler
* @p: task being dequeued
* @deq_flags: %SCX_DEQ_*
*
@@ -264,7 +264,7 @@ struct sched_ext_ops {
void (*dequeue)(struct task_struct *p, u64 deq_flags);
/**
- * dispatch - Dispatch tasks from the BPF scheduler and/or user DSQs
+ * @dispatch: Dispatch tasks from the BPF scheduler and/or user DSQs
* @cpu: CPU to dispatch tasks for
* @prev: previous task being switched out
*
@@ -287,7 +287,7 @@ struct sched_ext_ops {
void (*dispatch)(s32 cpu, struct task_struct *prev);
/**
- * tick - Periodic tick
+ * @tick: Periodic tick
* @p: task running currently
*
* This operation is called every 1/HZ seconds on CPUs which are
@@ -297,7 +297,7 @@ struct sched_ext_ops {
void (*tick)(struct task_struct *p);
/**
- * runnable - A task is becoming runnable on its associated CPU
+ * @runnable: A task is becoming runnable on its associated CPU
* @p: task becoming runnable
* @enq_flags: %SCX_ENQ_*
*
@@ -324,7 +324,7 @@ struct sched_ext_ops {
void (*runnable)(struct task_struct *p, u64 enq_flags);
/**
- * running - A task is starting to run on its associated CPU
+ * @running: A task is starting to run on its associated CPU
* @p: task starting to run
*
* See ->runnable() for explanation on the task state notifiers.
@@ -332,7 +332,7 @@ struct sched_ext_ops {
void (*running)(struct task_struct *p);
/**
- * stopping - A task is stopping execution
+ * @stopping: A task is stopping execution
* @p: task stopping to run
* @runnable: is task @p still runnable?
*
@@ -343,7 +343,7 @@ struct sched_ext_ops {
void (*stopping)(struct task_struct *p, bool runnable);
/**
- * quiescent - A task is becoming not runnable on its associated CPU
+ * @quiescent: A task is becoming not runnable on its associated CPU
* @p: task becoming not runnable
* @deq_flags: %SCX_DEQ_*
*
@@ -363,7 +363,7 @@ struct sched_ext_ops {
void (*quiescent)(struct task_struct *p, u64 deq_flags);
/**
- * yield - Yield CPU
+ * @yield: Yield CPU
* @from: yielding task
* @to: optional yield target task
*
@@ -378,7 +378,7 @@ struct sched_ext_ops {
bool (*yield)(struct task_struct *from, struct task_struct *to);
/**
- * core_sched_before - Task ordering for core-sched
+ * @core_sched_before: Task ordering for core-sched
* @a: task A
* @b: task B
*
@@ -396,7 +396,7 @@ struct sched_ext_ops {
bool (*core_sched_before)(struct task_struct *a, struct task_struct *b);
/**
- * set_weight - Set task weight
+ * @set_weight: Set task weight
* @p: task to set weight for
* @weight: new weight [1..10000]
*
@@ -405,7 +405,7 @@ struct sched_ext_ops {
void (*set_weight)(struct task_struct *p, u32 weight);
/**
- * set_cpumask - Set CPU affinity
+ * @set_cpumask: Set CPU affinity
* @p: task to set CPU affinity for
* @cpumask: cpumask of cpus that @p can run on
*
@@ -415,7 +415,7 @@ struct sched_ext_ops {
const struct cpumask *cpumask);
/**
- * update_idle - Update the idle state of a CPU
+ * @update_idle: Update the idle state of a CPU
* @cpu: CPU to udpate the idle state for
* @idle: whether entering or exiting the idle state
*
@@ -436,7 +436,7 @@ struct sched_ext_ops {
void (*update_idle)(s32 cpu, bool idle);
/**
- * cpu_acquire - A CPU is becoming available to the BPF scheduler
+ * @cpu_acquire: A CPU is becoming available to the BPF scheduler
* @cpu: The CPU being acquired by the BPF scheduler.
* @args: Acquire arguments, see the struct definition.
*
@@ -446,7 +446,7 @@ struct sched_ext_ops {
void (*cpu_acquire)(s32 cpu, struct scx_cpu_acquire_args *args);
/**
- * cpu_release - A CPU is taken away from the BPF scheduler
+ * @cpu_release: A CPU is taken away from the BPF scheduler
* @cpu: The CPU being released by the BPF scheduler.
* @args: Release arguments, see the struct definition.
*
@@ -458,7 +458,7 @@ struct sched_ext_ops {
void (*cpu_release)(s32 cpu, struct scx_cpu_release_args *args);
/**
- * init_task - Initialize a task to run in a BPF scheduler
+ * @init_task: Initialize a task to run in a BPF scheduler
* @p: task to initialize for BPF scheduling
* @args: init arguments, see the struct definition
*
@@ -473,8 +473,9 @@ struct sched_ext_ops {
s32 (*init_task)(struct task_struct *p, struct scx_init_task_args *args);
/**
- * exit_task - Exit a previously-running task from the system
+ * @exit_task: Exit a previously-running task from the system
* @p: task to exit
+ * @args: exit arguments, see the struct definition
*
* @p is exiting or the BPF scheduler is being unloaded. Perform any
* necessary cleanup for @p.
@@ -482,7 +483,7 @@ struct sched_ext_ops {
void (*exit_task)(struct task_struct *p, struct scx_exit_task_args *args);
/**
- * enable - Enable BPF scheduling for a task
+ * @enable: Enable BPF scheduling for a task
* @p: task to enable BPF scheduling for
*
* Enable @p for BPF scheduling. enable() is called on @p any time it
@@ -491,7 +492,7 @@ struct sched_ext_ops {
void (*enable)(struct task_struct *p);
/**
- * disable - Disable BPF scheduling for a task
+ * @disable: Disable BPF scheduling for a task
* @p: task to disable BPF scheduling for
*
* @p is exiting, leaving SCX or the BPF scheduler is being unloaded.
@@ -501,7 +502,7 @@ struct sched_ext_ops {
void (*disable)(struct task_struct *p);
/**
- * dump - Dump BPF scheduler state on error
+ * @dump: Dump BPF scheduler state on error
* @ctx: debug dump context
*
* Use scx_bpf_dump() to generate BPF scheduler specific debug dump.
@@ -509,7 +510,7 @@ struct sched_ext_ops {
void (*dump)(struct scx_dump_ctx *ctx);
/**
- * dump_cpu - Dump BPF scheduler state for a CPU on error
+ * @dump_cpu: Dump BPF scheduler state for a CPU on error
* @ctx: debug dump context
* @cpu: CPU to generate debug dump for
* @idle: @cpu is currently idle without any runnable tasks
@@ -521,7 +522,7 @@ struct sched_ext_ops {
void (*dump_cpu)(struct scx_dump_ctx *ctx, s32 cpu, bool idle);
/**
- * dump_task - Dump BPF scheduler state for a runnable task on error
+ * @dump_task: Dump BPF scheduler state for a runnable task on error
* @ctx: debug dump context
* @p: runnable task to generate debug dump for
*
@@ -532,7 +533,7 @@ struct sched_ext_ops {
#ifdef CONFIG_EXT_GROUP_SCHED
/**
- * cgroup_init - Initialize a cgroup
+ * @cgroup_init: Initialize a cgroup
* @cgrp: cgroup being initialized
* @args: init arguments, see the struct definition
*
@@ -547,7 +548,7 @@ struct sched_ext_ops {
struct scx_cgroup_init_args *args);
/**
- * cgroup_exit - Exit a cgroup
+ * @cgroup_exit: Exit a cgroup
* @cgrp: cgroup being exited
*
* Either the BPF scheduler is being unloaded or @cgrp destroyed, exit
@@ -556,7 +557,7 @@ struct sched_ext_ops {
void (*cgroup_exit)(struct cgroup *cgrp);
/**
- * cgroup_prep_move - Prepare a task to be moved to a different cgroup
+ * @cgroup_prep_move: Prepare a task to be moved to a different cgroup
* @p: task being moved
* @from: cgroup @p is being moved from
* @to: cgroup @p is being moved to
@@ -571,7 +572,7 @@ struct sched_ext_ops {
struct cgroup *from, struct cgroup *to);
/**
- * cgroup_move - Commit cgroup move
+ * @cgroup_move: Commit cgroup move
* @p: task being moved
* @from: cgroup @p is being moved from
* @to: cgroup @p is being moved to
@@ -582,7 +583,7 @@ struct sched_ext_ops {
struct cgroup *from, struct cgroup *to);
/**
- * cgroup_cancel_move - Cancel cgroup move
+ * @cgroup_cancel_move: Cancel cgroup move
* @p: task whose cgroup move is being canceled
* @from: cgroup @p was being moved from
* @to: cgroup @p was being moved to
@@ -594,7 +595,7 @@ struct sched_ext_ops {
struct cgroup *from, struct cgroup *to);
/**
- * cgroup_set_weight - A cgroup's weight is being changed
+ * @cgroup_set_weight: A cgroup's weight is being changed
* @cgrp: cgroup whose weight is being updated
* @weight: new weight [1..10000]
*
@@ -608,7 +609,7 @@ struct sched_ext_ops {
*/
/**
- * cpu_online - A CPU became online
+ * @cpu_online: A CPU became online
* @cpu: CPU which just came up
*
* @cpu just came online. @cpu will not call ops.enqueue() or
@@ -617,7 +618,7 @@ struct sched_ext_ops {
void (*cpu_online)(s32 cpu);
/**
- * cpu_offline - A CPU is going offline
+ * @cpu_offline: A CPU is going offline
* @cpu: CPU which is going offline
*
* @cpu is going offline. @cpu will not call ops.enqueue() or
@@ -630,12 +631,12 @@ struct sched_ext_ops {
*/
/**
- * init - Initialize the BPF scheduler
+ * @init: Initialize the BPF scheduler
*/
s32 (*init)(void);
/**
- * exit - Clean up after the BPF scheduler
+ * @exit: Clean up after the BPF scheduler
* @info: Exit info
*
* ops.exit() is also called on ops.init() failure, which is a bit
@@ -645,17 +646,17 @@ struct sched_ext_ops {
void (*exit)(struct scx_exit_info *info);
/**
- * dispatch_max_batch - Max nr of tasks that dispatch() can dispatch
+ * @dispatch_max_batch: Max nr of tasks that dispatch() can dispatch
*/
u32 dispatch_max_batch;
/**
- * flags - %SCX_OPS_* flags
+ * @flags: %SCX_OPS_* flags
*/
u64 flags;
/**
- * timeout_ms - The maximum amount of time, in milliseconds, that a
+ * @timeout_ms: The maximum amount of time, in milliseconds, that a
* runnable task should be able to wait before being scheduled. The
* maximum timeout may not exceed the default timeout of 30 seconds.
*
@@ -664,13 +665,13 @@ struct sched_ext_ops {
u32 timeout_ms;
/**
- * exit_dump_len - scx_exit_info.dump buffer length. If 0, the default
+ * @exit_dump_len: scx_exit_info.dump buffer length. If 0, the default
* value of 32768 is used.
*/
u32 exit_dump_len;
/**
- * hotplug_seq - A sequence number that may be set by the scheduler to
+ * @hotplug_seq: A sequence number that may be set by the scheduler to
* detect when a hotplug event has occurred during the loading process.
* If 0, no detection occurs. Otherwise, the scheduler will fail to
* load if the sequence number does not match @scx_hotplug_seq on the
@@ -679,7 +680,7 @@ struct sched_ext_ops {
u64 hotplug_seq;
/**
- * name - BPF scheduler's name
+ * @name: BPF scheduler's name
*
* Must be a non-zero valid BPF object name including only isalnum(),
* '_' and '.' chars. Shows up in kernel.sched_ext_ops sysctl while the
@@ -960,7 +961,7 @@ static DEFINE_PER_CPU(struct task_struct *, direct_dispatch_task);
static struct scx_dispatch_q **global_dsqs;
static const struct rhashtable_params dsq_hash_params = {
- .key_len = 8,
+ .key_len = sizeof_field(struct scx_dispatch_q, id),
.key_offset = offsetof(struct scx_dispatch_q, id),
.head_offset = offsetof(struct scx_dispatch_q, hash_node),
};
@@ -1408,7 +1409,6 @@ static struct task_struct *scx_task_iter_next(struct scx_task_iter *iter)
/**
* scx_task_iter_next_locked - Next non-idle task with its rq locked
* @iter: iterator to walk
- * @include_dead: Whether we should include dead tasks in the iteration
*
* Visit the non-idle task with its rq lock held. Allows callers to specify
* whether they would like to filter out dead tasks. See scx_task_iter_start()
@@ -3136,6 +3136,7 @@ static struct task_struct *pick_task_scx(struct rq *rq)
* scx_prio_less - Task ordering for core-sched
* @a: task A
* @b: task B
+ * @in_fi: in forced idle state
*
* Core-sched is implemented as an additional scheduling layer on top of the
* usual sched_class'es and needs to find out the expected task ordering. For
@@ -3184,6 +3185,10 @@ static bool test_and_clear_cpu_idle(int cpu)
* scx_pick_idle_cpu() can get caught in an infinite loop as
* @cpu is never cleared from idle_masks.smt. Ensure that @cpu
* is eventually cleared.
+ *
+ * NOTE: Use cpumask_intersects() and cpumask_test_cpu() to
+ * reduce memory writes, which may help alleviate cache
+ * coherence pressure.
*/
if (cpumask_intersects(smt, idle_masks.smt))
cpumask_andnot(idle_masks.smt, idle_masks.smt, smt);
@@ -3220,6 +3225,74 @@ found:
}
/*
+ * Return the amount of CPUs in the same LLC domain of @cpu (or zero if the LLC
+ * domain is not defined).
+ */
+static unsigned int llc_weight(s32 cpu)
+{
+ struct sched_domain *sd;
+
+ sd = rcu_dereference(per_cpu(sd_llc, cpu));
+ if (!sd)
+ return 0;
+
+ return sd->span_weight;
+}
+
+/*
+ * Return the cpumask representing the LLC domain of @cpu (or NULL if the LLC
+ * domain is not defined).
+ */
+static struct cpumask *llc_span(s32 cpu)
+{
+ struct sched_domain *sd;
+
+ sd = rcu_dereference(per_cpu(sd_llc, cpu));
+ if (!sd)
+ return 0;
+
+ return sched_domain_span(sd);
+}
+
+/*
+ * Return the amount of CPUs in the same NUMA domain of @cpu (or zero if the
+ * NUMA domain is not defined).
+ */
+static unsigned int numa_weight(s32 cpu)
+{
+ struct sched_domain *sd;
+ struct sched_group *sg;
+
+ sd = rcu_dereference(per_cpu(sd_numa, cpu));
+ if (!sd)
+ return 0;
+ sg = sd->groups;
+ if (!sg)
+ return 0;
+
+ return sg->group_weight;
+}
+
+/*
+ * Return the cpumask representing the NUMA domain of @cpu (or NULL if the NUMA
+ * domain is not defined).
+ */
+static struct cpumask *numa_span(s32 cpu)
+{
+ struct sched_domain *sd;
+ struct sched_group *sg;
+
+ sd = rcu_dereference(per_cpu(sd_numa, cpu));
+ if (!sd)
+ return NULL;
+ sg = sd->groups;
+ if (!sg)
+ return NULL;
+
+ return sched_group_span(sg);
+}
+
+/*
* Return true if the LLC domains do not perfectly overlap with the NUMA
* domains, false otherwise.
*/
@@ -3250,19 +3323,10 @@ static bool llc_numa_mismatch(void)
* overlapping, which is incorrect (as NUMA 1 has two distinct LLC
* domains).
*/
- for_each_online_cpu(cpu) {
- const struct cpumask *numa_cpus;
- struct sched_domain *sd;
-
- sd = rcu_dereference(per_cpu(sd_llc, cpu));
- if (!sd)
+ for_each_online_cpu(cpu)
+ if (llc_weight(cpu) != numa_weight(cpu))
return true;
- numa_cpus = cpumask_of_node(cpu_to_node(cpu));
- if (sd->span_weight != cpumask_weight(numa_cpus))
- return true;
- }
-
return false;
}
@@ -3280,8 +3344,7 @@ static bool llc_numa_mismatch(void)
static void update_selcpu_topology(void)
{
bool enable_llc = false, enable_numa = false;
- struct sched_domain *sd;
- const struct cpumask *cpus;
+ unsigned int nr_cpus;
s32 cpu = cpumask_first(cpu_online_mask);
/*
@@ -3295,10 +3358,12 @@ static void update_selcpu_topology(void)
* CPUs.
*/
rcu_read_lock();
- sd = rcu_dereference(per_cpu(sd_llc, cpu));
- if (sd) {
- if (sd->span_weight < num_online_cpus())
+ nr_cpus = llc_weight(cpu);
+ if (nr_cpus > 0) {
+ if (nr_cpus < num_online_cpus())
enable_llc = true;
+ pr_debug("sched_ext: LLC=%*pb weight=%u\n",
+ cpumask_pr_args(llc_span(cpu)), llc_weight(cpu));
}
/*
@@ -3310,15 +3375,19 @@ static void update_selcpu_topology(void)
* enabling both NUMA and LLC optimizations is unnecessary, as checking
* for an idle CPU in the same domain twice is redundant.
*/
- cpus = cpumask_of_node(cpu_to_node(cpu));
- if ((cpumask_weight(cpus) < num_online_cpus()) && llc_numa_mismatch())
- enable_numa = true;
+ nr_cpus = numa_weight(cpu);
+ if (nr_cpus > 0) {
+ if (nr_cpus < num_online_cpus() && llc_numa_mismatch())
+ enable_numa = true;
+ pr_debug("sched_ext: NUMA=%*pb weight=%u\n",
+ cpumask_pr_args(numa_span(cpu)), numa_weight(cpu));
+ }
rcu_read_unlock();
pr_debug("sched_ext: LLC idle selection %s\n",
- enable_llc ? "enabled" : "disabled");
+ str_enabled_disabled(enable_llc));
pr_debug("sched_ext: NUMA idle selection %s\n",
- enable_numa ? "enabled" : "disabled");
+ str_enabled_disabled(enable_numa));
if (enable_llc)
static_branch_enable_cpuslocked(&scx_selcpu_topo_llc);
@@ -3348,6 +3417,8 @@ static void update_selcpu_topology(void)
* 4. Pick a CPU within the same NUMA node, if enabled:
* - choose a CPU from the same NUMA node to reduce memory access latency.
*
+ * 5. Pick any idle CPU usable by the task.
+ *
* Step 3 and 4 are performed only if the system has, respectively, multiple
* LLC domains / multiple NUMA nodes (see scx_selcpu_topo_llc and
* scx_selcpu_topo_numa).
@@ -3364,7 +3435,6 @@ static s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu,
*found = false;
-
/*
* This is necessary to protect llc_cpus.
*/
@@ -3383,15 +3453,10 @@ static s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu,
*/
if (p->nr_cpus_allowed >= num_possible_cpus()) {
if (static_branch_maybe(CONFIG_NUMA, &scx_selcpu_topo_numa))
- numa_cpus = cpumask_of_node(cpu_to_node(prev_cpu));
-
- if (static_branch_maybe(CONFIG_SCHED_MC, &scx_selcpu_topo_llc)) {
- struct sched_domain *sd;
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kernel/sched/sched.h
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