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60c27fb59f
Add ops.cpu_online/offline() which are invoked when CPUs come online and
offline respectively. As the enqueue path already automatically bypasses
tasks to the local dsq on a deactivated CPU, BPF schedulers are guaranteed
to see tasks only on CPUs which are between online() and offline().
If the BPF scheduler doesn't implement ops.cpu_online/offline(), the
scheduler is automatically exited with SCX_ECODE_RESTART |
SCX_ECODE_RSN_HOTPLUG. Userspace can implement CPU hotpplug support
trivially by simply reinitializing and reloading the scheduler.
scx_qmap is updated to print out online CPUs on hotplug events. Other
schedulers are updated to restart based on ecode.
v3: - The previous implementation added @reason to
sched_class.rq_on/offline() to distinguish between CPU hotplug events
and topology updates. This was buggy and fragile as the methods are
skipped if the current state equals the target state. Instead, add
scx_rq_[de]activate() which are directly called from
sched_cpu_de/activate(). This also allows ops.cpu_on/offline() to
sleep which can be useful.
- ops.dispatch() could be called on a CPU that the BPF scheduler was
told to be offline. The dispatch patch is updated to bypass in such
cases.
v2: - To accommodate lock ordering change between scx_cgroup_rwsem and
cpus_read_lock(), CPU hotplug operations are put into its own SCX_OPI
block and enabled eariler during scx_ope_enable() so that
cpus_read_lock() can be dropped before acquiring scx_cgroup_rwsem.
- Auto exit with ECODE added.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Vernet <dvernet@meta.com>
Acked-by: Josh Don <joshdon@google.com>
Acked-by: Hao Luo <haoluo@google.com>
Acked-by: Barret Rhoden <brho@google.com>
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| .. | ||
| autogroup.c | ||
| autogroup.h | ||
| build_policy.c | ||
| build_utility.c | ||
| clock.c | ||
| completion.c | ||
| core_sched.c | ||
| core.c | ||
| cpuacct.c | ||
| cpudeadline.c | ||
| cpudeadline.h | ||
| cpufreq_schedutil.c | ||
| cpufreq.c | ||
| cpupri.c | ||
| cpupri.h | ||
| cputime.c | ||
| deadline.c | ||
| debug.c | ||
| ext.c | ||
| ext.h | ||
| fair.c | ||
| features.h | ||
| idle.c | ||
| isolation.c | ||
| loadavg.c | ||
| Makefile | ||
| membarrier.c | ||
| pelt.c | ||
| pelt.h | ||
| psi.c | ||
| rt.c | ||
| sched-pelt.h | ||
| sched.h | ||
| smp.h | ||
| stats.c | ||
| stats.h | ||
| stop_task.c | ||
| swait.c | ||
| syscalls.c | ||
| topology.c | ||
| wait_bit.c | ||
| wait.c | ||