Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
sched_ext: Don't kick CPUs running higher classes
When a sched_ext scheduler tries to kick a CPU, the CPU may be running a
higher class task. sched_ext has no control over such CPUs. A sched_ext
scheduler couldn't have expected to get access to the CPU after kicking it
anyway. Skip kicking when the target CPU is running a higher class.
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
+8
-3
+8
-3
kernel/sched/ext.c
+8
-3
kernel/sched/ext.c
···
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{
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struct rq *rq = cpu_rq(cpu);
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struct scx_rq *this_scx = &this_rq->scx;
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+
const struct sched_class *cur_class;
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bool should_wait = false;
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unsigned long flags;
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raw_spin_rq_lock_irqsave(rq, flags);
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cur_class = rq->curr->sched_class;
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/*
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* During CPU hotplug, a CPU may depend on kicking itself to make
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-
* forward progress. Allow kicking self regardless of online state.
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* forward progress. Allow kicking self regardless of online state. If
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* @cpu is running a higher class task, we have no control over @cpu.
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* Skip kicking.
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*/
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-
if (cpu_online(cpu) || cpu == cpu_of(this_rq)) {
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+
if ((cpu_online(cpu) || cpu == cpu_of(this_rq)) &&
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!sched_class_above(cur_class, &ext_sched_class)) {
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if (cpumask_test_cpu(cpu, this_scx->cpus_to_preempt)) {
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-
if (rq->curr->sched_class == &ext_sched_class)
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+
if (cur_class == &ext_sched_class)
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rq->curr->scx.slice = 0;
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cpumask_clear_cpu(cpu, this_scx->cpus_to_preempt);
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}