mirror_ubuntu-kernels/kernel/sched
Valentin Schneider 68f4ff04db sched, smp: Trace smp callback causing an IPI
Context
=======

The newly-introduced ipi_send_cpumask tracepoint has a "callback" parameter
which so far has only been fed with NULL.

While CSD_TYPE_SYNC/ASYNC and CSD_TYPE_IRQ_WORK share a similar backing
struct layout (meaning their callback func can be accessed without caring
about the actual CSD type), CSD_TYPE_TTWU doesn't even have a function
attached to its struct. This means we need to check the type of a CSD
before eventually dereferencing its associated callback.

This isn't as trivial as it sounds: the CSD type is stored in
__call_single_node.u_flags, which get cleared right before the callback is
executed via csd_unlock(). This implies checking the CSD type before it is
enqueued on the call_single_queue, as the target CPU's queue can be flushed
before we get to sending an IPI.

Furthermore, send_call_function_single_ipi() only has a CPU parameter, and
would need to have an additional argument to trickle down the invoked
function. This is somewhat silly, as the extra argument will always be
pushed down to the function even when nothing is being traced, which is
unnecessary overhead.

Changes
=======

send_call_function_single_ipi() is only used by smp.c, and is defined in
sched/core.c as it contains scheduler-specific ops (set_nr_if_polling() of
a CPU's idle task).

Split it into two parts: the scheduler bits remain in sched/core.c, and the
actual IPI emission is moved into smp.c. This lets us define an
__always_inline helper function that can take the related callback as
parameter without creating useless register pressure in the non-traced path
which only gains a (disabled) static branch.

Do the same thing for the multi IPI case.

Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230307143558.294354-8-vschneid@redhat.com
2023-03-24 11:01:29 +01:00
..
autogroup.c sched/all: Change all BUG_ON() instances in the scheduler to WARN_ON_ONCE() 2022-08-12 11:25:10 +02:00
autogroup.h sched/headers: Add header guard to kernel/sched/stats.h and kernel/sched/autogroup.h 2022-02-23 08:22:00 +01:00
build_policy.c sched: Fix missing prototype warnings 2022-05-01 10:03:43 +02:00
build_utility.c sched: Fix missing prototype warnings 2022-05-01 10:03:43 +02:00
clock.c sched/clock: Make local_clock() noinstr 2023-01-31 15:01:47 +01:00
completion.c sched/completion: Add wait_for_completion_state() 2022-09-07 21:53:49 +02:00
core_sched.c sched: Rename task_running() to task_on_cpu() 2022-09-07 21:53:47 +02:00
core.c sched, smp: Trace smp callback causing an IPI 2023-03-24 11:01:29 +01:00
cpuacct.c Merge branch 'sched/fast-headers' into sched/core 2022-03-15 09:05:05 +01:00
cpudeadline.c sched/core: Introduce sched_asym_cpucap_active() 2022-08-02 12:32:45 +02:00
cpudeadline.h
cpufreq_schedutil.c cpufreq: schedutil: make kobj_type structure constant 2023-02-23 19:57:29 +01:00
cpufreq.c sched/headers: Introduce kernel/sched/build_utility.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
cpupri.c sched/all: Change all BUG_ON() instances in the scheduler to WARN_ON_ONCE() 2022-08-12 11:25:10 +02:00
cpupri.h sched/cpupri: Add CPUPRI_HIGHER 2020-10-29 11:00:30 +01:00
cputime.c cputime: remove cputime_to_nsecs fallback 2022-12-27 12:52:17 +01:00
deadline.c sched/deadline: Add more reschedule cases to prio_changed_dl() 2023-02-11 11:18:10 +01:00
debug.c - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
fair.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
features.h sched/fair: Introduce SIS_UTIL to search idle CPU based on sum of util_avg 2022-06-28 09:08:30 +02:00
idle.c arch/idle: Change arch_cpu_idle() behavior: always exit with IRQs disabled 2023-01-13 11:48:15 +01:00
isolation.c sched/headers: Introduce kernel/sched/build_utility.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
loadavg.c sched/headers: Introduce kernel/sched/build_utility.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
Makefile sched/headers: Introduce kernel/sched/build_policy.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
membarrier.c sched/membarrier: Introduce MEMBARRIER_CMD_GET_REGISTRATIONS 2023-01-07 11:29:29 +01:00
pelt.c sched/headers: Introduce kernel/sched/build_policy.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
pelt.h sched/fair: Decay task PELT values during wakeup migration 2022-06-28 09:17:46 +02:00
psi.c sched/psi: Fix use-after-free in ep_remove_wait_queue() 2023-02-15 14:19:16 +01:00
rt.c sched/rt: pick_next_rt_entity(): check list_entry 2023-02-11 11:18:10 +01:00
sched-pelt.h sched/fair: Fix "runnable_avg_yN_inv" not used warnings 2019-06-17 12:15:58 +02:00
sched.h sched/fair: Remove capacity inversion detection 2023-02-11 11:18:09 +01:00
smp.h sched, smp: Trace smp callback causing an IPI 2023-03-24 11:01:29 +01:00
stats.c sched/headers: Introduce kernel/sched/build_utility.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
stats.h sched/psi: Use task->psi_flags to clear in CPU migration 2022-10-30 10:12:15 +01:00
stop_task.c sched: Add update_current_exec_runtime helper 2022-08-27 00:05:35 +02:00
swait.c sched/headers: Introduce kernel/sched/build_utility.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
topology.c Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
wait_bit.c wait_on_bit: add an acquire memory barrier 2022-08-26 09:30:25 -07:00
wait.c wait: Return number of exclusive waiters awaken 2022-11-16 11:33:03 -07:00