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sched_ext: Separate out scx_kick_cpu() and add @sch to it

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In preparation for multiple scheduler support, separate out scx_kick_cpu()
from scx_bpf_kick_cpu() and add the @sch parameter to it. scx_bpf_kick_cpu()
now acquires an RCU read lock, reads $scx_root, and calls scx_kick_cpu()
with it if non-NULL. The passed in @sch parameter is not used yet.

Internal uses of scx_bpf_kick_cpu() are converted to scx_kick_cpu(). Where
$sch is available, it's used. In the pick_task_scx() path where no
associated scheduler can be identified, $scx_root is used directly. Note
that $scx_root cannot be NULL in this case.

Reviewed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo
2025-09-23 09:03:26 -10:00
parent 7852e0fd1d
commit 9fc687edf2
1 changed files with 27 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

43
kernel/sched/ext.c
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@@ -136,7 +136,7 @@ static struct kset *scx_kset;
#include <trace/events/sched_ext.h>
static void process_ddsp_deferred_locals(struct rq *rq);
static void scx_bpf_kick_cpu(s32 cpu, u64 flags);
static void scx_kick_cpu(struct scx_sched *sch, s32 cpu, u64 flags);
static void scx_vexit(struct scx_sched *sch, enum scx_exit_kind kind,
s64 exit_code, const char *fmt, va_list args);
@@ -2125,10 +2125,10 @@ static int balance_one(struct rq *rq, struct task_struct *prev)
* balance(), we want to complete this scheduling cycle and then
* start a new one. IOW, we want to call resched_curr() on the
* next, most likely idle, task, not the current one. Use
* scx_bpf_kick_cpu() for deferred kicking.
* scx_kick_cpu() for deferred kicking.
*/
if (unlikely(!--nr_loops)) {
scx_bpf_kick_cpu(cpu_of(rq), 0);
scx_kick_cpu(sch, cpu_of(rq), 0);
break;
}
} while (dspc->nr_tasks);
@@ -2417,7 +2417,8 @@ static struct task_struct *pick_task_scx(struct rq *rq)
p = first_local_task(rq);
if (!p) {
if (kick_idle)
scx_bpf_kick_cpu(cpu_of(rq), SCX_KICK_IDLE);
scx_kick_cpu(rcu_dereference_sched(scx_root),
cpu_of(rq), SCX_KICK_IDLE);
return NULL;
}
@@ -3721,7 +3722,7 @@ static void scx_clear_softlockup(void)
*
* - pick_next_task() suppresses zero slice warning.
*
* - scx_bpf_kick_cpu() is disabled to avoid irq_work malfunction during PM
* - scx_kick_cpu() is disabled to avoid irq_work malfunction during PM
* operations.
*
* - scx_prio_less() reverts to the default core_sched_at order.
@@ -5809,17 +5810,7 @@ static const struct btf_kfunc_id_set scx_kfunc_set_unlocked = {
__bpf_kfunc_start_defs();
/**
* scx_bpf_kick_cpu - Trigger reschedule on a CPU
* @cpu: cpu to kick
* @flags: %SCX_KICK_* flags
*
* Kick @cpu into rescheduling. This can be used to wake up an idle CPU or
* trigger rescheduling on a busy CPU. This can be called from any online
* scx_ops operation and the actual kicking is performed asynchronously through
* an irq work.
*/
__bpf_kfunc void scx_bpf_kick_cpu(s32 cpu, u64 flags)
static void scx_kick_cpu(struct scx_sched *sch, s32 cpu, u64 flags)
{
struct rq *this_rq;
unsigned long irq_flags;
@@ -5872,6 +5863,26 @@ out:
local_irq_restore(irq_flags);
}
/**
* scx_bpf_kick_cpu - Trigger reschedule on a CPU
* @cpu: cpu to kick
* @flags: %SCX_KICK_* flags
*
* Kick @cpu into rescheduling. This can be used to wake up an idle CPU or
* trigger rescheduling on a busy CPU. This can be called from any online
* scx_ops operation and the actual kicking is performed asynchronously through
* an irq work.
*/
__bpf_kfunc void scx_bpf_kick_cpu(s32 cpu, u64 flags)
{
struct scx_sched *sch;
guard(rcu)();
sch = rcu_dereference(scx_root);
if (likely(sch))
scx_kick_cpu(sch, cpu, flags);
}
/**
* scx_bpf_dsq_nr_queued - Return the number of queued tasks
* @dsq_id: id of the DSQ