linux/kernel/sched
Keisuke Nishimura 6d7e4782bc sched/fair: Fix the decision for load balance
should_we_balance is called for the decision to do load-balancing.
When sched ticks invoke this function, only one CPU should return
true. However, in the current code, two CPUs can return true. The
following situation, where b means busy and i means idle, is an
example, because CPU 0 and CPU 2 return true.

        [0, 1] [2, 3]
         b  b   i  b

This fix checks if there exists an idle CPU with busy sibling(s)
after looking for a CPU on an idle core. If some idle CPUs with busy
siblings are found, just the first one should do load-balancing.

Fixes: b1bfeab9b0 ("sched/fair: Consider the idle state of the whole core for load balance")
Signed-off-by: Keisuke Nishimura <keisuke.nishimura@inria.fr>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20231031133821.1570861-1-keisuke.nishimura@inria.fr
2023-11-14 22:27:01 +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/headers: Remove duplicate header inclusions 2023-10-03 21:27:55 +02:00
clock.c Locking changes for v6.5: 2023-06-27 14:14:30 -07:00
completion.c sched: add a few helpers to wake up tasks on the current cpu 2023-07-17 16:08:08 -07:00
core_sched.c sched: Rename task_running() to task_on_cpu() 2022-09-07 21:53:47 +02:00
core.c As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
cpuacct.c Merge branch 'sched/fast-headers' into sched/core 2022-03-15 09:05:05 +01:00
cpudeadline.c sched/topology: Consolidate and clean up access to a CPU's max compute capacity 2023-10-09 12:59:48 +02:00
cpudeadline.h
cpufreq_schedutil.c Merge branch 'pm-cpufreq' 2023-10-26 15:14:38 +02:00
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/rt: Fix live lock between select_fallback_rq() and RT push 2023-09-28 22:58:13 +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: Fix stop_one_cpu_nowait() vs hotplug 2023-10-13 09:56:29 +02:00
debug.c sched/deadline: Make dl_rq->pushable_dl_tasks update drive dl_rq->overloaded 2023-09-29 10:20:21 +02:00
fair.c sched/fair: Fix the decision for load balance 2023-11-14 22:27:01 +01:00
features.h sched/fair: Remove SIS_PROP 2023-10-24 10:38:44 +02:00
idle.c Merge branch 'sched/urgent' into sched/core, to pick up fixes and refresh the branch 2023-10-07 11:32:24 +02:00
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: Make PELT acronym definition searchable 2023-10-13 09:56:30 +02:00
pelt.h sched/fair: Decay task PELT values during wakeup migration 2022-06-28 09:17:46 +02:00
psi.c sched/psi: Update poll => rtpoll in relevant comments 2023-10-16 13:42:49 +02:00
rt.c sched: Fix stop_one_cpu_nowait() vs hotplug 2023-10-13 09:56:29 +02:00
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 SIS_PROP 2023-10-24 10:38:44 +02:00
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/fair: Rename check_preempt_curr() to wakeup_preempt() 2023-09-19 10:40:10 +02:00
swait.c sched: add a few helpers to wake up tasks on the current cpu 2023-07-17 16:08:08 -07:00
topology.c sched/fair: Scan cluster before scanning LLC in wake-up path 2023-10-24 10:38:43 +02:00
wait_bit.c wait_on_bit: add an acquire memory barrier 2022-08-26 09:30:25 -07:00
wait.c sched: remove wait bookmarks 2023-10-18 14:34:18 -07:00