linux.git/Documentation/scheduler, branch v6.10

Merge tag 'v6.9-rc1' into sched/core, to pick up fixes and to refresh the branch

2024-03-25T10:32:29+00:00

Signed-off-by: Ingo Molnar

Merge tag 'sched-urgent-2024-03-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-03-24T18:11:05+00:00

Pull scheduler doc clarification from Thomas Gleixner:
 "A single update for the documentation of the base_slice_ns tunable to
  clarify that any value which is less than the tick slice has no effect
  because the scheduler tick is not guaranteed to happen within the set
  time slice"

* tag 'sched-urgent-2024-03-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/doc: Update documentation for base_slice_ns and CONFIG_HZ relation

sched/doc: Update documentation for base_slice_ns and CONFIG_HZ relation

2024-03-21T19:34:16+00:00

The tunable base_slice_ns is dependent on CONFIG_HZ (i.e. TICK_NSEC)
for any significant performance improvement. The reason being the
scheduler tick is not frequent enough to force preemption when
base_slice expires in case of:

           base_slice_ns < TICK_NSEC

The below data is of stress-ng:

	Number of CPU: 1
	Stressor threads: 4
	Time: 30sec

	On CONFIG_HZ=1000

	| base_slice | avg-run (msec) | context-switches |
	| ---------- | -------------- | ---------------- |
	| 3ms        | 2.914          | 10342            |
	| 6ms        | 4.857          | 6196             |
	| 9ms        | 6.754          | 4482             |
	| 12ms       | 7.872          | 3802             |
	| 22ms       | 11.294         | 2710             |
	| 32ms       | 13.425         | 2284             |

	On CONFIG_HZ=100

	| base_slice | avg-run (msec) | context-switches |
	| ---------- | -------------- | ---------------- |
	| 3ms        | 9.144          | 3337             |
	| 6ms        | 9.113          | 3301             |
	| 9ms        | 8.991          | 3315             |
	| 12ms       | 12.935         | 2328             |
	| 22ms       | 16.031         | 1915             |
	| 32ms       | 18.608         | 1622             |

	base_slice: the value of base_slice in ms
	avg-run (msec): average time of the stressor threads got on cpu before
	it got preempted
	context-switches: number of context switches for the stress-ng process

Signed-off-by: Mukesh Kumar Chaurasiya 
Signed-off-by: Ingo Molnar 
Cc: Randy Dunlap 
Link: https://lore.kernel.org/r/20240320173815.927637-2-mchauras@linux.ibm.com

sched/balancing: Rename load_balance() => sched_balance_rq()

2024-03-12T11:00:00+00:00

Standardize scheduler load-balancing function names on the
sched_balance_() prefix.

Also load_balance() has become somewhat of a misnomer: historically
it was the first and primary load-balancing function that was called,
but with the introduction of sched domains, it's become a lower
layer function that balances runqueues.

Rename it to sched_balance_rq() accordingly.

Signed-off-by: Ingo Molnar 
Reviewed-by: Shrikanth Hegde 
Link: https://lore.kernel.org/r/20240308111819.1101550-6-mingo@kernel.org

sched/balancing: Rename rebalance_domains() => sched_balance_domains()

2024-03-12T10:59:59+00:00

Standardize scheduler load-balancing function names on the
sched_balance_() prefix.

Signed-off-by: Ingo Molnar 
Reviewed-by: Shrikanth Hegde 
Link: https://lore.kernel.org/r/20240308111819.1101550-5-mingo@kernel.org

sched/balancing: Rename trigger_load_balance() => sched_balance_trigger()

2024-03-12T10:59:59+00:00

Standardize scheduler load-balancing function names on the
sched_balance_() prefix.

Signed-off-by: Ingo Molnar 
Reviewed-by: Shrikanth Hegde 
Link: https://lore.kernel.org/r/20240308111819.1101550-4-mingo@kernel.org

sched/balancing: Rename scheduler_tick() => sched_tick()

2024-03-12T10:59:59+00:00

- Standardize on prefixing scheduler-internal functions defined
  in  with sched_*() prefix. scheduler_tick() was
  the only function using the scheduler_ prefix. Harmonize it.

- The other reason to rename it is the NOHZ scheduler tick
  handling functions are already named sched_tick_*().
  Make the 'git grep sched_tick' more meaningful.

Signed-off-by: Ingo Molnar 
Acked-by: Valentin Schneider 
Reviewed-by: Shrikanth Hegde 
Link: https://lore.kernel.org/r/20240308111819.1101550-3-mingo@kernel.org

sched/balancing: Rename run_rebalance_domains() => sched_balance_softirq()

2024-03-12T10:59:59+00:00

run_rebalance_domains() is a misnomer, as it doesn't only
run rebalance_domains(), but since the introduction of the
NOHZ code it also runs nohz_idle_balance().

Rename it to sched_balance_softirq(), reflecting its more
generic purpose and that it's a softirq handler.

Signed-off-by: Ingo Molnar 
Reviewed-by: Valentin Schneider 
Reviewed-by: Shrikanth Hegde 
Link: https://lore.kernel.org/r/20240308111819.1101550-2-mingo@kernel.org

sched/debug: Increase SCHEDSTAT_VERSION to 16

2024-03-12T10:03:40+00:00

We changed the order of definitions within 'enum cpu_idle_type',
which changed the order of [CPU_MAX_IDLE_TYPES] columns in
show_schedstat().

Suggested-by: Shrikanth Hegde 
Signed-off-by: Ingo Molnar 
Cc: "Gautham R. Shenoy" 
Link: https://lore.kernel.org/r/20240308105901.1096078-5-mingo@kernel.org

membarrier: Create Documentation/scheduler/membarrier.rst

2024-02-15T16:04:12+00:00

To gather the architecture requirements of the "private/global
expedited" membarrier commands.  The file will be expanded to
integrate further information about the membarrier syscall (as
needed/desired in the future).  While at it, amend some related
inline comments in the membarrier codebase.

Suggested-by: Mathieu Desnoyers 
Signed-off-by: Andrea Parri 
Reviewed-by: Mathieu Desnoyers 
Link: https://lore.kernel.org/r/20240131144936.29190-3-parri.andrea@gmail.com
Signed-off-by: Palmer Dabbelt